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Chiral CNN Pincer Palladium(II) Complexes with 2‑Aryl-6(oxazolinyl)pyridine Ligands: Synthesis, Characterization, and Application to Enantioselective Allylation of Isatins and Suzuki− Miyaura Coupling Reaction Tao Wang, Xin-Qi Hao, Juan-Juan Huang, Kai Wang, Jun-Fang Gong,* and Mao-Ping Song* College of Chemistry and Molecular Engineering, Henan Key Laboratory of Chemical Biology and Organic Chemistry, Zhengzhou University, Zhengzhou 450001, People’s Republic of China S Supporting Information *

ABSTRACT: A series of chiral 2-aryl-6-(oxazolinyl)pyridine (aryl = phenyl or 1-naphthyl) ligands 2a−f were conveniently prepared from commercially available 6-bromo-2-picolinaldehyde in two steps. Reaction of 2a−f with PdCl2 in toluene in the presence of sodium bicarbonate afforded the corresponding CNN pincer Pd(II) complexes 3a−f via aryl C−H bond activation of the related ligands. All of the new compounds have been fully characterized by elemental analysis (MS for ligands), 1H and 13C NMR, and IR spectra. In addition, the molecular structures of Pd(II) complexes 3c−f have been determined by X-ray singlecrystal diffraction. The obtained chiral pincer catalysts were successfully used in the asymmetric allylation of isatins with allyltributyltin, giving the corresponding 3-allyl-3-hydroxyoxindoles in high yields with enantioselectivities of up to 86% ee. These pincers could also catalyze the asymmetric Suzuki−Miyaura coupling reaction to provide the axially chiral biaryl products in good yields with good stereoselectivities (up to 68% ee).

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INTRODUCTION Palladium-catalyzed reactions have played key roles for the synthesis of useful organic compounds in both academia and industry. An important and fascinating subclass of palladium catalysts are pincer palladium complexes, in which the terdentate ligand coordinates to the Pd(II) center in a meridional fashion through sigma and/or dative bonds to form two stable five- or six-membered palladacycles. These complexes have been found to be effective catalysts for numerous catalytic reactions such as aldol reaction, Michael addition, allylation of aldehydes and imines, and cross-coupling reactions including Heck, Suzuki, and Sonogashira reactions.1 Further, the applications of chiral pincer Pd(II) complexes in asymmetric catalytic reactions have attracted increasing attention in recent years, and good to excellent stereocontrol has been achieved. For example, the axially chiral 1,1′-bi-2naphthol- and 1,1′-biphenanthrol-based bis(phosphite) PCP pincer Pd complexes displayed good stereoselectivities in allylation of aldehydes (up to 62% ee) and sulfonimines (up © 2013 American Chemical Society

to 85% ee) as well as condensation of sulfonimines and isocyanoacetate (up to 86% ee).2 The bis(phosphine) PCP pincer Pd complexes bearing stereogenic benzylic methylene centers readily catalyzed the enantioselective hydrophosphination of several kinds of electron-deficient alkenes with diarylphosphines, giving the chiral phosphine derivatives with excellent enantioselectivities.3 The pyrroloimidazolone-based NCN pincer Pd complexes showed high levels of enantioselectivities (up to 83% ee) in the Michael reaction between vinyl ketones and α-cyanocarboxylates.4 The preliminary attempts using the bis(imidazolinyl)phenyl (Phebim) NCN pincer Pd(II) complexes, which were first reported by us, as the catalysts for the asymmetric addition of diphenylphosphine to chalcone afforded the expected adduct with up to 85% ee.5 During our study, Nakamura and co-workers6 also explored the applications of similar Pd-Phebim complexes in several catalytic Received: September 22, 2013 Published: December 11, 2013 194

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Scheme 1. Synthesis of Chiral CNN Pincer Pd(II) Complexes 3a−f with 2-Aryl-6-(oxazolinyl)pyridines

Figure 1. Molecular structures of the pincer Pd(II) complexes 3c (left) and 3d (right). Hydrogen atoms are omitted for clarity.

to extend the chiral pincer Pd chemistry, and also in continuation of our investigations on the pincer metal complexes,10 herein we would like to describe the chiral CNN pincer Pd(II) complexes based on 2-aryl-6-(oxazolinyl)pyridine ligands (aryl = phenyl or 1-naphthyl), which can also be conveniently prepared by using 6-bromo-2-picolinaldehyde as the starting material (Scheme 1). The synthesis and characterization of the new chiral CNN pincer Pd catalysts as well as their potential in the asymmetric allylation of isatins and the Suzuki−Miyaura coupling reaction are presented below.

asymmetric reactions, providing excellent enantioselectivities in all cases. In addition, Arai and co-workers demonstrated that the related bis(imidazolidine) NCN pincer Pd complexes were highly enantioselective catalysts for the reaction of nitroalkenes with malononitriles (up to 93% ee).7 Besides symmetrical PCP and NCN pincer Pd complexes, the unsymmetrical chiral PCN pincer Pd complexes also exhibited high stereocontrol in asymmetric catalysis. We recently developed a facile “one-pot phosphorylation/metalation” method for the preparation of a variety of achiral and chiral PCN pincer Pd(II) and Ni(II) complexes.5b,8 It was found that the chiral PCN Pd pincers containing aryl-based aminophosphine-imidazoline ligands could catalyze the asymmetric addition of diphenylphosphine to β-aryl enones, giving the corresponding phosphine derivatives in high yields and enantioselectivities (up to 94% ee).5b Despite the impressive progress made so far in the pincer Pd-catalyzed enantioselective reactions, actually, much less research has been done on chiral pincer Pd catalysts compared with that on achiral ones. The development of new chiral pincer Pd complexes with high catalytic activities and stereoselectivities will still be important contributions to the field of pincer chemistry. In a previous work, we reported the achiral CNN pincer Pd complexes with N-substituted-2aminomethyl-6-phenylpyridine ligands, which were easily synthesized from commercially available 6-bromo-2-picolinaldehyde in two steps. The Pd complexes were used as effective catalysts for allylation of aldehydes as well as three-component allylation of aldehydes, arylamines, and allyltributyltin.9 In order

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RESULTS AND DISCUSSION Synthesis of 2-Aryl-6-(oxazolinyl)pyridines and the Chiral CNN Pincer Pd(II) Complexes. The synthesis of the required chiral ligands 2a−f was easily done in a two-step sequence from commercially available 6-bromo-2-picolinaldehyde as shown in Scheme 1. First, the Suzuki coupling reaction of 6-bromo-2-picolinaldehyde with phenylboronic acid or 1naphthylboronic acid in the presence of Pd(PPh3)4 in toluene readily gave 6-aryl-2-picolinaldehyde 1. Then the aldehyde group in compound 1 was directly converted to oxazolines by reaction with various chiral amino alcohols including L-valinol, L-tert-leucinol, L-phenylalaninol, L-phenylglycinol, and (1R,2S)2-amino-1,2-diphenylethanol, respectively, according to a published procedure.11 The expected 2-aryl-6-(oxazolinyl)pyridines 2a−f were isolated in good yields (45−76%) after purification. With the ligands in hand, the palladation was carried out by refluxing the ligands 2a−f and PdCl2 in toluene 195

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Figure 2. Molecular structures of the pincer Pd(II) complexes 3e (left) and 3f (right). Hydrogen atoms and solvent molecules are omitted for clarity.

Table 1. Selected Bond Lengths (Å) and Angles (deg) for Complexes 3c−f Pd(1)−C(1) Pd(1)−N(1) Pd(1)−N(2) Pd(1)−Cl(1) N(1)−Pd(1)−C(1) N(1)−Pd(1)−N(2) C(1)−Pd(1)−N(2) N(1)−Pd(1)−Cl(1) C(1)−Pd(1)−Cl(1) N(2)−Pd(1)−Cl(1)

3c

3d

3e·(n-hexane)

(2 × 3f)·CH2Cl2

1.995(3) 1.975(3) 2.184(2) 2.3004(9) 81.28(11) 78.57(10) 159.84(11) 174.36(8) 97.84(9) 102.27(8)

2.004(7) 1.999(6) 2.202(5) 2.316(2) 81.2(3) 77.5(2) 158.5(3) 176.80(16) 97.3(2) 104.14(16)

1.995(6) 1.981(6) 2.215(4) 2.292(2) 81.7(3) 77.7(2) 159.3(2) 177.85(18) 96.6(2) 104.05(15)

1.981(4) 2.039(4) 2.110(3) 2.3218(15) 92.99(19) 81.37(15) 172.6(2) 167.24(11) 96.86(17) 89.44(12)

(around 77°) are small, which are in accordance with pincers consisting of two fused five-membered-ring palladacycles and reflect a relative steric strain of the system. In contrast to complexes 3c−e, complex 3f possesses one five-membered and one six-membered palladacycle. It was interesting to find that for ligand 2f the C-palladation occurred on the 8-position of naphthyl instead of the 2-position to afford complex 3f. If the palladation occurred on the 2-position, two fused fivemembered palladacycles would be formed. The reason for the outcome was possibly due to the higher electron density of the 8-position. In comparison with 3c−e, complex 3f has obviously different bond angles around the Pd(II) center (Table 1). The significantly bigger C(1)−Pd(1)−N(2) (around 173° vs 159°) angle in complex 3f suggests that introduction of a larger metallacycle decreases the steric strain of the resultant complex. Similarly to the related CNN Pd complexes,9,12 the Pd−N(2) bond length in complexes 3c−f is also longer than that of Pd− N(1), which can be attributed to the higher trans influence of the metalated carbanion compared to the chloride ligand. Allylation of Isatins. Enantioenriched 3-substituted 3hydroxyoxindoles are important structural motifs for a large number of natural products and drug candidates.13 In particular, 3-allyl-3-hydroxyoxindoles are very useful because the double bond in the allyl group provides a functional handle for further transformations.14 As a consequence, development of practical methods for their preparation is of much interest. Several strategies including asymmetric hydroxylation of 3-allyl2-oxindoles15 and asymmetric allylation of isatins16 have been reported in the literature. Although the metal-catalyzed allylation of isatins is the most direct method, only a few metal catalysts have afforded high to excellent enantioselectivities.16f,h−j For example, the highest ee value was only 71% when chiral palladium-phosphoramidite complexes were used as the catalysts for the allylation of isatins with allylboron, which was generated in situ from allylic alcohol and excess triethylborane.16e In the present study, we found that the

in the presence of sodium bicarbonate to afford the air- and moisture-stable pincer complexes 3a−f in good yields (41− 55%). All of the chiral CNN pincer Pd complexes were fully characterized by elemental analysis, 1H NMR, 13C NMR, and IR spectra. In comparison with the 1H NMR spectra of the corresponding ligands 2a−f, one of the resonances in the downfield region (around 7−9 ppm) due to the aromatic protons in the Pd complexes 3a−f is absent, indicating the occurrence of C-palladation of the phenyl or naphthyl ring, and the signals of the oxazoline protons obviously shift downfield due to coordination of oxazoline-N to the Pd center. The 13C NMR spectra also show some evidence for the formation of pincer complexes. For example, four carbon signals are found for the 2-phenyl group in the ligands 2a−e, while six carbon signals correspond to the 2-phenyl group in the pincer Pd complexes 3a−e. Further, a new quarternary C-signal appears at around 153 ppm, which is assigned to the orthometalated carbon atom. Molecular Structures of the Chiral CNN Pincer Pd(II) Complexes. The molecular structures of pincer Pd complexes 3c−f were unambiguously determined by X-ray single-crystal analysis. The molecules are illustrated in Figures 1 and 2, respectively. Selected bond lengths and bond angles are listed in Table 1. The Pd(II) center in each complex adopts a distorted-square-planar configuration with the pincer ligand coordinated to the metal via the pendant phenyl- or naphthylC, pyridine-N, and oxazoline-N in a terdentate manner and the chloride ligand occupying the fourth coordination site. In the Pd complexes 3c−e the two formed palladacycles are both fivemembered rings, which are approximately coplanar with the central pyridine ring. All of the bond lengths and angles around the Pd(II) center in the three complexes are similar. The values of bond lengths and angles are comparable to those in the related achiral CNN Pd complexes.9,12 The N(1)−Pd(1)− C(1) angles (around 81°) and N(1)−Pd(1)−N(2) angles 196

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with decreased reaction temperature, and excellent yields were still achieved after 12 h (entries 7−9). For example, a 96% yield with 58% ee was obtained using complex 3b as the catalyst at −20 °C (entry 9). When the temperature was further lowered to −40 °C, a decrease in the enantioselectivitity was observed (45% ee, entry 10). The possible reason for the outcome was that the DCE solvent solidified at this temperature. Pleasingly, a 95% yield with 71% ee was achieved when the solvent was changed to CH2Cl2, which has a much lower freezing point than DCE (entry 11). Then several other solvents including CHCl3, CH3CN, and THF were also tested at −40 °C, and none of them gave better enantioselectivities than CH2Cl2 (entry 12−14). With CH2Cl2 as the solvent, the temperature was further lowered to −60 °C and the ee value could be improved to 78% without loss of activity (entry 15). When the reaction was conducted at −70 °C, the enantioselectivity was not enhanced further (entry 16), and a reduction in the catalyst loading from 5 mol % to 3 mol % led to decreased yield and enantioselectivity (entry 17). Allylation of N-benzylisatin (4a) with allyltrimethyl- or allyltrimethoxysilane as the allyl source was also tried. No reaction occurred at −60 °C or even at room temperature in CH2Cl2 with 5 mol % of complex 3b as the catalyst (data not shown in Table 2). In the presence of one equivalent of AgF6d as an additive, reaction of 4a with allyltrimethylsilane at room temperature could afford the product in a 50% yield wth only 15% ee (entry 18). A 46% yield wth 59% ee was obtained when the same reaction was conducted at −60 °C (entry 19). Another additive such as AgOAc, AgOTf, or AgBF4 was found to be ineffective for the reaction at this temperature (data not shown), and changing the solvent from CH2Cl2 to THF gave a racemic product (entry 20). The use of allyltrimethoxysilane as the allyl source did not provide better enantioselectivites either (entries 21 and 22). Thus, the optimized conditions for the allylation of isatin include using 5 mol % of complex 3b as the catalyst and allyltributyltin as the allyl source in CH2Cl2 at −60 °C for 12 h (entry 15). In addition, the allylation of a ketimine derived from 4a under similar reaction conditions was briefly investigated. The reaction proceeded much more slowly than that of 4a, and the best ee value achieved was 72% (Scheme 2, more results on this reaction are given in the Supporting Information). With the optimal conditions established, allylation of other isatins was investigated (Table 3). In all cases, the corresponding 3-allyl-3-hydroxyoxindole products were isolated in high yields (89−95%). The enantioselectivities of the products were generally good and found to be influenced by the N-protecting group and substituent on the isatins. For example, N-(p-methylbenzyl)- and N-(o-methylbenzyl)isatin afforded comparable enantioselectivities (6b and 6c) to that of N-benzylisatin, and a slightly increased enantioselectivity was obtained for N-methylisatin (82% ee, 6e). However, when 1naphthylmethyl and particularly trityl (Tr) were used as the Nprotecting group, the ee values decreased (6f and 6g). The

obtained chiral CNN pincer Pd complexes could exhibit high enantioselectivities in the enantioselective allylation of isatins with allyltributyltin as the nucleophilic allyl source. The experiments began with allylation of N-benzylisatin (4a) as the model reaction, which was carried out in the presence of 5 mol % of Pd complex in ClCH2CH2Cl (DCE) at room temperature for 2 h. Under the stated conditions, all of the six complexes 3a−f produced the expected 3-allyl-3-hydroxyoxindole 6a in excellent yields. However, the enantioselectivities of 6a were found to be only moderate in all cases (Table 2, Table 2. Optimization of Reaction Conditions for the Asymmetric Allylation of N-Benzylisatin Catalyzed by the Chiral CNN Pincer Pd(II) Complexes 3a

entry

cat.

allyl source

solvent

temp (°C)

1 2 3 4 5 6 7e 8e 9e 10e 11e 12e 13e 14e 15e 16e 17e,f 18e,g 19e,g 20e,g 21e,g 22e,g

3a 3b 3c 3d 3e 3f 3b 3e 3b 3b 3b 3b 3b 3b 3b 3b 3b 3b 3b 3b 3b 3b

5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5b 5b 5b 5c 5c

DCE DCE DCE DCE DCE DCE DCE DCE DCE DCE CH2Cl2 CHCl3 CH3CN THF CH2Cl2 CH2Cl2 CH2Cl2 CH2Cl2 CH2Cl2 THF CH2Cl2 THF

RT RT RT RT RT RT 0 0 −20 −40 −40 −40 −40 −40 −60 −70 −70 RT −60 −60 −60 −60

yield (%)b ee (%)c,d 96 98 93 97 95 91 97 95 96 92 95 98 87 97 94 91 88 50 46 40 82 80

32 35 30 29 36 24 50 51 58 45 71 63 42 44 78 77 68 15 59 0 10 24

a Reaction conditions: 4a (0.20 mmol), 5 (0.30 mmol), cat. 3 (5 mol %), solvent (1 mL), 2 h. bIsolated yields. cDetermined by chiral HPLC. dThe absolute configuration of the product was assigned to be S by comparison of the optical rotation with that in ref 16f. e12 h. fcat. 3b (3 mol %). gIn the presence of AgF (0.20 mmol) as an additive.

entries 1−6). Among them, complex 3b, with (4S)-tert-butyl, and 3e, with (4S,5R)-4,5-diphenyl substituents, gave relatively higher enantioselectivities (35% and 36% ee, respectively, entries 2 and 5). The enantioselectivities could be improved

Scheme 2. Asymmetric Allylation of a Ketimine Derived from N-Benzylisatin Catalyzed by the Chiral CNN Pincer Pd(II) Complex 3e

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Table 3. Substrate Scope for the Asymmetric Allylation of Isatins Catalyzed by the Chiral CNN Pincer Pd(II) Complex 3ba

Reaction conditions: 4 (0.20 mmol), allyltributyltin (0.30 mmol), cat. 3b (5 mol %), CH2Cl2 (1 mL), −60 °C, 12 h. Yields are isolated yields, and the ee values were determined by chiral HPLC. The absolute configurations of the known products were assigned to be S by comparison of optical rotations with those in refs 16f and i, and the configurations of the new products were assigned by analogy. a

electron-donating group such as 5-Me on isatin showed some beneficial effect on the enantioselectivities of the catalysis products (83−86% ee, 6j, 6k, and 6l), while an electronwithdrawing group such as 6-Br displayed slightly inferior stereocontrol (6r and 6s). Other substituent such as 4-Br, 5-

isatin without an N-protecting group also gave a reduced ee value of 60% (6d). In this case, allylation at nitrogen was not observed, which was in contrast to the chiral palladiumphosphoramidite catalyst.16e In comparison with the related Nprotected unsubstituted isatins (78−82% ee, 6a, 6b, and 6e), an 198

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isolated in a 85% yield with 43% ee after 24 h (entry 1). When K2CO3 as the base was used, the yield drastically decreased while the enantioselectivity improved (47% yield with 52% ee, entry 2). Other bases afforded rather low ee values or trace amounts of product (entries 3−5). Lowering the reaction temperature from 80 °C to 50 °C could not give better enantioselectivity (entry 6 vs entry 1). Since K2CO3 produced a relatively higher ee, it was selected as the base in the following experiments. By prolonging the reaction time to 48 h the product 9a was obtained in a 71% yield with 50% ee (entry 7 vs entry 2). Then the other five pincer Pd complexes 3a,b and 3d−f were examined, and all of them gave inferior enantioselectivities (31−48% ee, entries 8−12). Therefore, the optimized conditions include using complex 3c as the catalyst with K2CO3 base at 80 °C for 48 h (entry 7). We next explored the substrate scope. As shown in Table 5, the coupling reaction of 1-iodo-2-ethoxynaphthalene and 1-iodo-2-benzyloxynaphthalene provided comparable results to that of 1-iodo-2methoxynaphthalene with 1-naphthaleneboronic acid (9a−9c), and the coupling of these iodides with 2-methyl or 2phenylbenzeneboronic acid gave only low enantioselectivities (21−29% ee) although excellent yields could be achieved (9d− 9g). When 1-pyreneboronic acid was used as the coupling partner, moderate enantioselectivities were obtained (9h and 9i, 39% and 43% ee, respectively). Finally, the coupling of 9phenanthreneboronic acid with the aforementioned iodides afforded good enantioselectivities (62−68% ee, 9j−9l).

MeO, 5-F, 5-Cl, 5-Br, and 7-Br gave comparable results (6h, 6i, 6m−6q, 6t, and 6u). Asymmetric Suzuki−Miyaura Coupling Reaction. The cross-coupling of organic halides and organoboron reagents, known as the Suzuki−Miyaura coupling, is one of the most efficient methods to create carbon−carbon bonds and thus has found widespread applications in organic synthesis.17 Although the reaction has been widely utilized for the synthesis of achiral biaryl compounds, there are relatively few reports to date dealing with asymmetric biaryl synthesis involving Suzuki− Miyaura cross-coupling reactions. Among them, most of the examples concern the use of chiral palladium-phosphine complexes as catalysts, giving axially chiral biaryl compounds with enantioselectivities from moderate to high.18 Recently, C2symmetric bis-hydrazones19 and ADCs (acyclic diaminocarbenes)20 appear as new, phosphine-free chiral ligands for this reaction, and the first palladium-diene-catalyzed asymmetric Suzuki−Miyaura coupling reaction has been achieved by the research group of Lin.21 In addition, the chiral pincer Pd(II) complexes including the NCN complexes with bis(oxazolinyl)phenyl (Phebox) ligands22 and PCN complexes with (imidazolinyl)aryl phosphinite ligands8c have also been used as catalysts for the coupling. Overall, the obtained enantiomeric excesses by the above pincer catalysts are rather modest (300 °C. [α]20D = +0.298 (c 0.110, CH2Cl2). IR (KBr): ν 2963, 2868, 1584, 1462, 1415, 1380, 1366, 1283, 1260, 1242, 1182, 1118, 1068, 1022, 951, 918, 819, 765, 748, 728, 711, 690, 636 cm−1. 1H NMR (400 MHz, CDCl3): δ 7.83 (t, J = 7.8 Hz, 2H, ArH), 7.60 (d, J = 8.2 Hz, 1H, ArH), 7.38 (d, J = 7.6 Hz, 1H, ArH), 7.30 (dd, J = 1.8, 7.3 Hz, 1H, ArH), 7.13−7.05 (m, 2H, ArH), 4.73−4.64 (m, 2H, OxH), 4.17 (dd, J = 5.2, 9.6 Hz, 1H, OxH), 1.07 (s, 9H, C(CH3)3). 13C NMR (100 MHz, CDCl3): δ 166.8, 165.3, 151.5, 145.2, 143.5, 138.9, 137.0, 130.8,

124.9, 124.0, 120.8, 120.2, 73.1, 72.7, 34.6, 26.2. Anal. Calcd for C18H19ClN2OPd (421.23): C, 51.32; H, 4.55; N, 6.65. Found: C, 51.44; H, 4.50; N, 6.49. [(S)-4-Phenyl-2-(6-phenylpyridin-2-yl)-4,5-dihydrooxazole]palladium(II) Chloride (3c). Orange solid (45.9 mg, 52%). Mp: 297− 299 °C. [α]20D = +0.457 (c 0.130, CH2Cl2). IR (KBr): ν 3036, 1584, 1466, 1454, 1422, 1385, 1355, 1327, 1277, 1247, 1235, 1190, 1156, 1069, 1025, 1002, 936, 925, 820, 770, 750, 728, 697, 617, 553, 453 cm−1. 1H NMR (400 MHz, d6-DMSO): δ 8.21−8.14 (m, 2H, ArH), 7.72 (dd, J = 1.5, 7.0 Hz, 1H, ArH), 7.66 (dd, J = 1.8, 7.4 Hz, 1H, ArH), 7.51−7.48 (m, 3H, ArH), 7.43−7.39 (m, 2H, ArH), 7.37−7.32 (m, 1H, ArH), 7.14−7.06 (m, 2H, ArH), 5.49 (dd, J = 6.6, 10.2 Hz, 1H, OxH), 5.23 (dd, J = 8.9, 10.2 Hz, 1H, OxH), 4.77 (dd, J = 6.7, 8.8 Hz, 1H, OxH). 13C NMR (100 MHz, d6-DMSO): δ 167.8, 164.4, 152.6, 146.0, 143.0, 140.5, 139.7, 135.7, 129.9, 128.5, 127.8, 127.1, 124.84, 124.78, 122.1, 121.5, 78.2, 65.8. Anal. Calcd for C20H15ClN2OPd (441.22): C, 54.44; H, 3.43; N, 6.35. Found: C, 54.44; H, 3.32; N, 6.15. [(S)-4-Benzyl-2-(6-phenylpyridin-2-yl)-4,5-dihydrooxazole]palladium(II) Chloride (3d). Orange solid (50.0 mg, 55%). Mp: 233− 234 °C. [α]20D = +0.241 (c 0.100, CH2Cl2). IR (KBr): ν 3023, 2942, 1636, 1586, 1497, 1463, 1455, 1436, 1422, 1385, 1312, 1269, 1242, 1190, 1151, 1117, 1068, 1024, 942, 869, 808, 763, 733, 724, 696, 638, 580, 450 cm−1. 1H NMR (400 MHz, CDCl3): δ 7.62−7.55 (m, 2H, ArH), 7.34 (d, J = 8.4 Hz, 3H, ArH), 7.29−7.26 (m, 2H, ArH), 7.23− 7.19 (m, 1H, ArH), 7.16−7.13 (m, 1H, ArH), 7.08 (d, J = 7.6 Hz, 1H, ArH), 7.04−6.97 (m, 2H, ArH), 4.97−4.89 (m, 2H, OxH), 4.50−4.43 (m, 1H, OxH), 3.48 (dd, J = 2.8, 14.0 Hz, 1H, CHHPh), 3.08 (dd, J = 7.7, 14.0 Hz, 1H, CHHPh). 13C NMR (100 MHz, CDCl3): δ 167.3, 165.1, 153.5, 145.6, 143.6, 138.7, 136.3, 136.1, 130.4, 129.8, 128.6, 126.8, 124.6, 123.8, 120.4, 120.1, 75.1, 64.7, 39.4. Anal. Calcd for C21H17ClN2OPd (455.25): C, 55.40; H, 3.76; N, 6.15. Found: C, 55.42; H, 3.68; N, 5.93. [(4S,5R)-4,5-Diphenyl-2-(6-phenylpyridin-2-yl)-4,5dihydrooxazole]palladium(II) Chloride (3e). Orange solid (42.4 mg, 41%). Mp: 279−281 °C. [α]20D = +0.235 (c 0.100, CH2Cl2). IR (KBr): ν 3032, 1580, 1495, 1454, 1419, 1379, 1341, 1316, 1286, 1208, 1187, 1156, 1117, 1068, 1023, 952, 812, 766, 739, 725, 696, 654, 636, 600, 584, 454 cm−1. 1H NMR (400 MHz, CDCl3): δ 7.67−7.63 (m, 2H, ArH), 7.41 (d, J = 7.8 Hz, 1H, ArH), 7.32 (d, J = 7.6 Hz, 1H, ArH), 7.20−7.16 (m, 1H, ArH), 7.10−7.05 (m, 6H, ArH), 7.02−7.00 (m, 4H, ArH), 6.95−6.93 (m, 2H, ArH), 6.57 (d, J = 10.4 Hz, 1H, OxH), 6.02 (d, J = 10.4 Hz, 1H, OxH). 13C NMR (100 MHz, CDCl3): δ 168.2, 165.2, 153.1, 145.4, 143.8, 138.7, 136.6, 134.8, 134.1, 130.6, 128.3, 127.9, 127.8, 127.5, 126.9, 124.6, 123.8, 120.52, 120.46, 89.7, 70.9. Anal. Calcd for C26H19ClN2OPd (517.31): C, 60.37; H, 3.70; N, 5.42. Found: C, 60.34; H, 3.69; N, 5.26. [(S)-4-Phenyl-2-(6-(naphthalen-1-yl)pyridin-2-yl)-4,5dihydrooxazole]palladium(II) chloride (3f). Orange solid (49.2 mg, 50%). Mp: 225−227 °C. [α]20D = +638 (c 0.104, CH2Cl2). IR (KBr): ν 3044, 1656, 1594, 1493, 1467, 1440, 1418, 1379, 1353, 1325, 1266, 1185, 1158, 922, 808, 765, 732, 695, 543 cm−1. 1H NMR (400 MHz, d6-DMSO): δ 8.80 (d, J = 8.0 Hz, 1H, ArH), 8.51 (d, J = 7.3 Hz, 1H, ArH), 8.44−8.39 (m, 2H, ArH), 8.11 (d, J = 8.2 Hz, 2H, ArH), 7.71 (d, J = 7.2 Hz, 1H, ArH), 7.65 (t, J = 7.8 Hz, 1H, ArH), 7.44−7.42 (m, 2H, ArH), 7.35 (t, J = 7.3 Hz, 2H, ArH), 7.31−7.28 (m, 1H, ArH), 7.23 (t, J = 7.6 Hz, 1H, ArH), 5.61 (dd, J = 5.6, 10.0 Hz, 1H, OxH), 5.27 (dd, J = 8.9, 9.8 Hz, 1H, OxH), 4.79 (dd, J = 5.7, 8.8 Hz, 1H, OxH). 13C NMR (100 MHz, d6-DMSO): δ 167.1, 153.2, 144.3, 140.5, 139.3, 138.7, 137.0, 134.3, 133.0, 132.5, 130.0, 129.1, 128.3, 127.6, 127.1, 126.9, 125.9, 124.4, 124.3, 123.9, 78.9, 65.8. Anal. Calcd for C24H17ClN2OPd·0.5CH2Cl2 (533.74): C, 55.13; H, 3.40; N, 5.25. Found: C, 55.35; H, 3.38; N, 5.36. General Procedure for the Catalytic Asymmetric Allylation of Isatins. Under an argon atmosphere, a Schlenk tube equipped with a magnetic stirring bar was charged with the pincer Pd catalyst 3 (5 mol %), isatin (0.20 mmol), and CH2Cl2 (1 mL). The reaction mixture was stirred at −60 °C; then allyltributyltin (0.30 mmol, 93.0 μL) was added. After the resulting solution mixture was stirred at that temperature for 12 h, the residue was purified by preparative TLC on 201

dx.doi.org/10.1021/om400945d | Organometallics 2014, 33, 194−205

Organometallics

Article

propanol = 90/10, flow = 1.0 mL/min, and detected at a UV wavelength of 254 nm. Retention times: 10.3 min, 39.3 min (major), 77% ee. [α]20D = +25.8 (c 0.852, CH2Cl2). 1H NMR (400 MHz, CDCl3): δ 7.31−7.23 (m, 5H, ArH), 7.14 (d, J = 8.1 Hz, 1H, ArH), 7.02 (t, J = 8.0 Hz, 1H, ArH), 6.59 (d, J = 7.7 Hz, 1H, ArH), 5.41− 5.27 (m, 1H, CH2CHCH2), 5.13 (d, J = 16.9 Hz, 1H, CH2Ph), 5.03−4.94 (m, 2H, CH2CHCH2), 4.66 (d, J = 15.8 Hz, 1H, CH2Ph), 3.69 (br s, 1H, OH), 3.35−3.30 (m, 1H, CH2CHCH2), 2.94−2.88 (m, 1H, CH2CHCH2). 13C NMR (100 MHz, CDCl3): δ 176.9, 144.6, 134.9, 130.9, 130.1, 128.8, 127.8, 127.5, 127.3, 127.2, 120.5, 119.4, 108.6, 77.9, 43.9, 40.1. HRMS (positive ESI; m/z): [M + H]+ calcd for C18H17BrNO2 358.0443, found 358.0451. (S)-3-Allyl-4-bromo-3-hydroxy-1-methylindolin-2-one (6i). Colorless oil (50.8 mg, 90%). The enantiomeric excess was determined on a Daicel Chiralcel OJ-H column with hexane/2-propanol = 90/10, flow = 1.0 mL/min, and detected at a UV wavelength of 254 nm. Retention times: 9.2 min, 10.5 min (major), 84% ee. [α]20D = +5.4 (c 0.910, CH2Cl2). 1H NMR (400 MHz, CDCl3): δ 7.21−7.15 (m, 2H, ArH), 6.75 (dd, J = 1.4, 7.0 Hz, 1H, ArH), 5.38−5.28 (m, 1H, CH2CH CH2), 5.11−5.06 (m, 1H, CH2CHCH2), 4.95−4.92 (m, 1H, CH2CHCH2), 3.47 (br s, 1H, OH), 3.25−3.20 (m, 1H, CH2CH CH2), 3.14 (s, 3H, CH3), 2.87−2.82 (m, 1H, CH2CHCH2). 13C NMR (100 MHz, CDCl3): δ 176.6, 145.4, 131.0, 129.9, 127.5, 127.2, 120.2, 119.4, 107.4, 77.9, 40.0, 26.2. HRMS (positive ESI; m/z): [M + H]+ calcd for C12H13BrNO2 282.0130, found 282.0139. (S)-3-Allyl-3-hydroxy-5-methyl-1-(4-methylbenzyl)indolin-2-one (6k). White solid (57.2 mg, 93%). Mp: 123−124 °C. The enantiomeric excess was determined on a Daicel Chiralcel OD-H column with hexane/2-propanol = 80/20, flow = 1.0 mL/min, and detected at a UV wavelength of 254 nm. Retention times: 4.9 min, 6.0 min (major), 83% ee. [α]20D = +10.8 (c 0.878, CH2Cl2). 1H NMR (400 MHz, CDCl3): δ 7.21 (s, 1H, ArH), 7.14 (d, J = 8.0 Hz, 2H, ArH), 7.07 (d, J = 8.0 Hz, 2H, ArH), 6.96 (d, J = 8.0 Hz, 1H, ArH), 6.56 (d, J = 7.9 Hz, 1H, ArH), 5.64−5.53 (m, 1H, CH2CHCH2), 5.15−5.04 (m, 2H, CH2CHCH2), 4.92 (d, J = 15.6 Hz, 1H, CH2Ph), 4.61 (d, J = 15.6 Hz, 1H, CH2Ph), 3.83 (br s, 1H, OH), 2.83−2.78 (m, 1H, CH2CH CH2), 2.74−2.69 (m, 1H, CH2CHCH2), 2.28 (s, 6H, CH3). 13C NMR (100 MHz, CDCl3): δ 178.0, 140.1, 137.2, 132.6, 132.5, 130.8, 129.9, 129.7, 129.4, 127.3, 124.9, 120.3, 109.3, 76.2, 43.6, 43.0, 21.08, 21.06. HRMS (positive ESI; m/z): [M + Na]+ calcd for C20H21NNaO2 330.1470, found 330.1479. (S)-3-Allyl-5-chloro-3-hydroxy-1-(4-methylbenzyl)indolin-2-one (6p). Colorless oil (60.3 mg, 92%). The enantiomeric excess was determined on a Daicel Chiralcel OD-H column with hexane/2propanol = 80/20, flow =1.0 mL/min, and detected at a UV wavelength of 254 nm. Retention times: 5.5 min, 7.2 min (major), 77% ee. [α]20D = +12.2 (c 0.933, CH2Cl2). 1H NMR (400 MHz, CDCl3): δ 7.36 (d, J = 2.1 Hz, 1H, ArH), 7.15−7.07 (m, 5H, ArH), 6.58 (d, J = 8.3 Hz, 1H, ArH), 5.61−5.51 (m, 1H, CH2CHCH2), 5.14−5.07 (m, 2H, CH2CHCH2), 4.92 (d, J = 15.6 Hz, 1H, CH2Ph), 4.61 (d, J = 15.6 Hz, 1H, CH2Ph), 4.12 (br s, 1H, OH), 2.83−2.78 (m, 1H, CH2CHCH2), 2.73−2.67 (m, 1H, CH2CH CH2), 2.29 (s, 3H, CH3). 13C NMR (100 MHz, CDCl3): δ 177.7, 140.9, 137.5, 131.9, 131.6, 130.1, 129.5, 129.4, 128.5, 127.3, 124.7, 120.8, 110.6, 76.1, 43.7, 42.9, 21.1. HRMS (positive ESI; m/z): [M + Na]+ calcd for C19H18ClNNaO2 350.0924, found 350.0917. (S)-3-Allyl-6-bromo-3-hydroxy-1-methylindolin-2-one (6s). Colorless oil (53.0 mg, 94%). The enantiomeric excess was determined on a Daicel Chiralcel OJ-H column with hexane/2-propanol = 90/10, flow = 1.0 mL/min, and detected at a UV wavelength of 254 nm. Retention times: 10.3 min (major), 14.0 min, 76% ee. [α]20D = −6.3 (c 0.772, CH2Cl2). 1H NMR (400 MHz, CDCl3): δ 7.25−7.21 (m, 2H, ArH), 6.97 (s, 1H, ArH), 5.64−5.53 (m, 1H, CH2CHCH2), 5.09−5.06 (m, 2H, CH2CHCH2), 3.76 (br s, 1H, OH), 3.13 (s, 3H, CH3), 2.75− 2.70 (m, 1H, CH2CHCH2), 2.61−2.55 (m, 1H, CH2CHCH2). 13 C NMR (100 MHz, CDCl3): δ 177.8, 144.5, 130.1, 128.7, 125.8, 125.5, 123.3, 120.6, 112.0, 75.7, 42.7, 26.3. HRMS (positive ESI; m/z): [M + H]+ calcd for C12H13BrNO2 282.0130, found 282.0137. (S)-3-Allyl-1-benzyl-7-bromo-3-hydroxyindolin-2-one (6t). Colorless oil (68.1 mg, 95%). The enantiomeric excess was determined on a

silica gel plates eluting with CH2Cl2/ethyl acetate to afford the corresponding catalysis products. The analytical data of the new catalysis products are given here, and those of the known products are shown in the Supporting Information. (S)-3-Allyl-3-hydroxy-1-(4-methylbenzyl)indolin-2-one (6b). White solid (55.7 mg, 95%). Mp: 128−130 °C. The enantiomeric excess was determined on a Daicel Chiralcel OJ-H column with hexane/2-propanol = 95/5, flow = 1.0 mL/min, and detected at a UV wavelength of 254 nm. Retention times: 15.5 min, 31.9 min (major), 79% ee. [α]20D = −0.4 (c 0.664, CH2Cl2). 1H NMR (400 MHz, CDCl3): δ 7.38 (d, J = 7.4 Hz, 1H, ArH), 7.20−7.15 (m, 3H, ArH), 7.10−7.02 (m, 3H, ArH), 6.69 (d, J = 7.8 Hz, 1H, ArH), 5.65−5.55 (m, 1H, CH2CHCH2), 5.14−5.06 (m, 2H, CH2CHCH2), 4.95 (d, J = 15.6 Hz, 1H, CH2Ph), 4.65 (d, J = 15.6 Hz, 1H, CH2Ph), 3.62 (br s, 1H, OH), 2.84−2.79 (m, 1H, CH2CHCH2), 2.73−2.67 (m, 1H, CH2CHCH2), 2.29 (s, 3H, CH3). 13C NMR (100 MHz, CDCl3): δ 178.0, 142.5, 137.3, 132.4, 130.6, 129.8, 129.5, 129.4, 127.3, 124.1, 123.0, 120.4, 109.5, 76.0, 43.6, 43.0, 21.1. HRMS (positive ESI; m/z): [M + Na]+ calcd for C19H19NNaO2 316.1313, found 316.1307. (S)-3-Allyl-3-hydroxy-1-(2-methylbenzyl)indolin-2-one (6c). White solid (53.4 mg, 91%). Mp: 141−143 °C. The enantiomeric excess was determined on a Daicel Chiralcel OD-H column with hexane/2propanol = 80/20, flow = 1.0 mL/min, and detected at a UV wavelength of 254 nm. Retention times: 5.6 min, 9.3 min (major), 76% ee. [α]20D = +3.5 (c 0.572, CH2Cl2). 1H NMR (400 MHz, CDCl3): δ 7.42 (d, J = 7.3 Hz, 1H, ArH), 7.19−7.14 (m, 3H, ArH), 7.09−7.01 (m, 3H, ArH), 6.58 (d, J = 7.8 Hz, 1H, ArH), 5.72−5.62 (m, 1H, CH2CHCH2), 5.16−5.10 (m, 2H, CH2CHCH2), 4.98 (d, J = 16.4 Hz, 1H, CH2Ph), 4.70 (d, J = 16.4 Hz, 1H, CH2Ph), 3.67 (br s, 1H, OH), 2.87−2.82 (m, 1H, CH2CHCH2), 2.75−2.70 (m, 1H, CH2CHCH2), 2.37 (s, 3H, CH3). 13C NMR (100 MHz, CDCl3): δ 178.1, 142.7, 135.6, 132.8, 130.65, 130.57, 129.8, 129.6, 127.5, 126.3, 126.2, 124.2, 123.1, 120.6, 109.7, 76.0, 43.0, 42.0, 19.3. HRMS (positive ESI; m/z): [M + Na]+ calcd for C19H19NNaO2 316.1313, found 316.1309. (S)-3-Allyl-3-hydroxy-1-(naphthalen-1-ylmethyl)indolin-2-one (6f). White solid (59.3 mg, 90%). Mp: 143−145 °C. The enantiomeric excess was determined on a Daicel Chiralcel OD-H column with hexane/2-propanol = 80/20, flow = 1.0 mL/min, and detected at a UV wavelength of 254 nm. Retention times: 8.2 min, 16.9 min (major), 68% ee. [α]20D = +11.1 (c 0.966, CH2Cl2). 1H NMR (400 MHz, CDCl3): δ 8.09 (d, J = 8.3 Hz, 1H, ArH), 7.88 (d, J = 7.6 Hz, 1H, ArH), 7.78 (d, J = 8.1 Hz, 1H, ArH), 7.59−7.51 (m, 2H, ArH), 7.41 (d, J = 6.8 Hz, 1H, ArH), 7.36 (t, J = 7.6 Hz, 1H, ArH), 7.29 (d, J = 6.8 Hz, 1H, ArH), 7.17−7.12 (m, 1H, ArH), 7.05 (t, J = 7.3 Hz, 1H, ArH), 6.66 (d, J = 7.8 Hz, 1H, ArH), 5.76−5.65 (m, 1H, CH2CHCH2), 5.55 (d, J = 16.2 Hz, 1H, NCH2), 5.18−5.11 (m, 3H, NCH2, CH2CHCH2), 3.28 (br s, 1H, OH), 2.87−2.82 (m, 1H, CH2CH CH2), 2.75−2.70 (m, 1H, CH2CHCH2). 13C NMR (100 MHz, CDCl3): δ 178.0, 142.8, 133.9, 131.0, 130.5, 130.2, 129.72, 129.66, 128.9, 128.4, 126.6, 126.0, 125.2, 124.7, 124.1, 123.1, 122.9, 120.7, 109.9, 76.0, 43.1, 42.1. HRMS (positive ESI; m/z): [M + Na]+ calcd for C22H19NNaO2 352.1313, found 352.1310. (S)-3-Allyl-3-hydroxy-1-tritylindolin-2-one (6g). White solid (78.5 mg, 91%). Mp: 149−150 °C. The enantiomeric excess was determined on a Daicel Chiralcel OJ-H column with hexane/2-propanol = 95/5, flow = 1.0 mL/min, and detected at a UV wavelength of 254 nm. Retention times: 8.8 min, 14.8 min (major), 32% ee. [α]20D = −3.0 (c 0.500, CH2Cl2). 1H NMR (400 MHz, CDCl3): δ 7.41 (d, J = 7.2 Hz, 6H, ArH), 7.33−7.31 (m, 1H, ArH), 7.25−7.17 (m, 9H, ArH), 6.96− 6.87 (m, 2H, ArH), 6.28 (d, J = 8.0 Hz, 1H, ArH), 5.72−5.61 (m, 1H, CH2CHCH2), 5.18−5.14 (m, 2H, CH2CHCH2), 2.80−2.75 (m, 1H, CH2CHCH2), 2.72−2.67 (m, 1H, CH2CHCH2). 13C NMR (100 MHz, CDCl3): δ 179.8, 143.0, 141.8, 131.0, 130.0, 129.4, 129.1, 128.3, 128.1, 127.7, 127.0, 125.3, 123.4, 122.6, 120.4, 116.1, 75.6, 74.6, 44.1. HRMS (positive ESI; m/z): [M + Na]+ calcd for C30H25NNaO2 454.1783, found 454.1779. (S)-3-Allyl-1-benzyl-4-bromo-3-hydroxyindolin-2-one (6h). White solid (63.7 mg, 89%). Mp: 154−155 °C. The enantiomeric excess was determined on a Daicel Chiralcel OJ-H column with hexane/2202

dx.doi.org/10.1021/om400945d | Organometallics 2014, 33, 194−205

Organometallics

Article

Daicel Chiralcel OJ-H column with hexane/2-propanol = 90/10, flow = 1.0 mL/min, and detected at a UV wavelength of 254 nm. Retention times: 10.2 min, 17.9 min (major), 76% ee. [α]20D = −9.3 (c 0.973, CH2Cl2). 1H NMR (400 MHz, CDCl3): δ 7.35 (d, J = 7.7 Hz, 2H, ArH), 7.29−7.24 (m, 2H, ArH), 7.23−7.17 (m, 3H, ArH), 6.92 (t, J = 7.7 Hz, 1H, ArH), 5.60−5.50 (m, 1H, CH2CHCH2), 5.35−5.26 (m, 2H, CH2Ph), 5.10−5.04 (m, 2H, CH2CHCH2), 4.06 (br s, 1H, OH), 2.81−2.76 (m, 1H, CH2CHCH2), 2.73−2.68 (m, 1H, CH2CHCH2). 13C NMR (100 MHz, CDCl3): δ 179.0, 140.0, 137.0, 135.5, 133.2, 130.1, 128.5, 127.1, 126.4, 124.5, 123.4, 120.9, 102.8, 75.3, 44.6, 43.3. HRMS (positive ESI; m/z): [M + Na]+ calcd for C18H16BrNNaO2 380.0262, found 380.0263. (S)-3-Allyl-7-bromo-3-hydroxy-1-methylindolin-2-one (6u). White solid (53.6 mg, 95%). Mp: 106−108 °C. The enantiomeric excess was determined on a Daicel Chiralcel OJ-H column with hexane/2propanol = 90/10, flow = 1.0 mL/min, and detected at a UV wavelength of 254 nm. Retention times: 6.8 min (major), 8.7 min, 81% ee. [α]20D = −17.4 (c 0.614, CH2Cl2). 1H NMR (400 MHz, CDCl3): δ 7.42 (d, J = 8.2 Hz, 1H, ArH), 7.31 (d, J = 7.3 Hz, 1H, ArH), 6.94 (t, J = 7.7 Hz, 1H, ArH), 5.63−5.52 (m, 1H, CH2CH CH2), 5.10−5.06 (m, 2H, CH2CHCH2), 3.66 (br s, 1H, OH), 3.53 (s, 3H, CH3), 2.74−2.69 (m, 1H, CH2CHCH2), 2.64−2.58 (m, 1H, CH2CHCH2). 13C NMR (100 MHz, CDCl3): δ 178.4, 140.5, 135.2, 133.0, 130.1, 124.3, 123.2, 120.7, 102.7, 75.4, 43.2, 29.8. HRMS (positive ESI; m/z): [M + Na]+ calcd for C12H12BrNNaO2 303.9949, found 303.9954. General Procedure for the Catalytic Asymmetric Suzuki− Miyaura Coupling Reaction. A Schlenk flask was charged with 1iodo-2-methoxynaphthalene (0.20 mmol), 1-naphthaleneboronic acid (0.30 mmol), pincer palladium complex 3 (5 mol %), K2CO3 (1.0 mmol), and DCE (2 mL). The mixture was stirred at 80 °C for 48 h under N2. After cooling, the reaction mixture was evaporated and the product was isolated by preparative TLC on silica gel plates. The analytical data of the new catalysis products are given here, and those of the known products are shown in the Supporting Information. (S)-2-Ethoxy-1-(o-tolyl)naphthalene (9e). White solid (50.4 mg, 96%). Mp: 86−87 °C. The enantiomeric excess was determined on a Daicel Chiralpak AD-H column with hexane/2-propanol = 98/2, flow = 0.8 mL/min, and detected at a UV wavelength of 254 nm. Retention times: 4.8 min, 6.1 min (major), 29% ee. [α]20D = +18.0 (c 0.508, CH2Cl2). 1H NMR (400 MHz, CDCl3): δ 7.85 (d, J = 9.0 Hz, 1H, ArH), 7.83−7.80 (m, 1H, ArH), 7.35−7.26 (m, 7H, ArH), 7.17 (d, J = 7.2 Hz, 1H, ArH), 4.08 (q, J = 7.0 Hz, 2H, OCH2CH3), 2.00 (s, 3H, CH3), 1.21 (t, J = 7.0 Hz, 3H, OCH2CH3). 13C NMR (100 MHz, CDCl3): δ 153.0, 137.6, 136.3, 133.6, 130.9, 129.7, 129.2, 128.9, 127.8, 127.3, 126.2, 125.54, 125.45, 125.2, 123.5, 115.6, 65.1, 19.8, 15.1. HRMS (positive ESI; m/z): [M + H]+ calcd for C19H19O 263.1436, found 263.1434. (S)-2-(Benzyloxy)-1-(o-tolyl)naphthalene (9f). White solid (60.3 mg, 93%). Mp: 53−54 °C. The enantiomeric excess was determined on a Daicel Chiralpak AD-H column with hexane/2-propanol = 98/2, flow = 0.8 mL/min, and detected at a UV wavelength of 254 nm. Retention times: 7.8 min, 9.4 min (major), 21% ee. [α]20D = +9.5 (c 0.888, CH2Cl2). 1H NMR (400 MHz, CDCl3): δ 7.83−7.79 (m, 2H, ArH), 7.36−7.29 (m, 7H, ArH), 7.27−7.19 (m, 4H, ArH), 7.13 (d, J = 6.5 Hz, 2H, ArH), 5.08 (s, 2H, OCH2C6H5), 2.00 (s, 3H, CH3). 13C NMR (100 MHz, CDCl3): δ 152.9, 137.7, 137.6, 136.2, 133.6, 131.0, 129.9, 129.4, 128.9, 128.4, 127.9, 127.6, 127.5, 126.9, 126.4, 126.2, 125.6, 125.3, 123.9, 116.2, 71.5, 19.9. HRMS (positive ESI; m/z): [M + H]+ calcd for C24H21O 325.1592, found 325.1591. (R)-1-(2-Methoxynaphthalen-1-yl)pyrene (9h). White solid (61.7 mg, 86%). Mp: 205−207 °C. The enantiomeric excess was determined on a Daicel Chiralpak AD-H column with hexane/2-propanol = 98/2, flow = 0.8 mL/min, and detected at a UV wavelength of 254 nm. Retention times: 9.3 min, 10.9 min (major), 39% ee. [α]20D = −39.6 (c 0.580, CH2Cl2). 1H NMR (400 MHz, CDCl3): δ 8.30 (d, J = 7.8 Hz, 1H, ArH), 8.19−8.09 (m, 4H, ArH), 8.03−7.94 (m, 3H, ArH), 7.90 (d, J = 8.2 Hz, 1H, ArH), 7.86 (d, J = 9.2 Hz, 1H, ArH), 7.57 (d, J = 9.2 Hz, 1H, ArH), 7.48 (d, J = 9.1 Hz, 1H, ArH), 7.35−7.31 (m, 1H, ArH), 7.22−7.16 (m, 1H, ArH), 7.11 (d, J = 8.5 Hz, 1H, ArH), 3.74 (s,

3H, OCH3). 13C NMR (100 MHz, CDCl3): δ 154.9, 134.5, 132.1, 131.4, 131.2, 130.9, 130.3, 129.7, 129.1, 129.0, 127.9, 127.6, 127.4, 126.6, 125.9, 125.8, 125.6, 125.1, 125.01, 124.97, 124.8, 123.7, 123.6, 113.9, 56.8. HRMS (positive ESI; m/z): [M + H]+ calcd for C27H19O 359.1436, found 359.1438. (R)-1-(2-Ethoxynaphthalen-1-yl)pyrene (9i). White solid (69.3 mg, 93%). Mp: 157−159 °C. The enantiomeric excess was determined on a Daicel Chiralpak AD-H column with hexane/2-propanol = 98/2, flow = 0.8 mL/min, and detected at a UV wavelength of 254 nm. Retention times: 7.7 min, 11.7 min (major), 43% ee. [α]20D = −25.3 (c 0.724, CH2Cl2). 1H NMR (400 MHz, CDCl3): δ 8.30 (d, J = 7.8 Hz, 1H, ArH), 8.22−8.12 (m, 4H, ArH), 8.02−7.95 (m, 3H, ArH), 7.91− 7.86 (m, 2H, ArH), 7.59 (d, J = 9.2 Hz, 1H, ArH), 7.48 (d, J = 9.0 Hz, 1H, ArH), 7.34 (t, J = 6.9 Hz, 1H, ArH), 7.21−7.17 (m, 1H, ArH), 7.12 (d, J = 8.6 Hz, 1H, ArH), 4.08−3.99 (m, 2H, OCH2CH3), 1.00 (t, J = 7.0 Hz, 3H, OCH2CH3). 13C NMR (100 MHz, CDCl3): δ 154.2, 134.5, 132.3, 131.4, 131.1, 130.7, 130.2, 129.5, 129.2, 129.1, 127.9, 127.6, 127.3, 127.1, 126.4, 125.91, 125.85, 125.7, 125.0, 124.92, 124.89, 124.7, 124.6, 123.7, 115.8, 65.4, 15.0. HRMS (positive ESI; m/ z): [M + H]+ calcd for C28H21O 373.1592, found 373.1591. (S)-9-(2-Methoxynaphthalen-1-yl)phenanthrene (9j). White solid (49.5 mg, 74%). Mp: 213−214 °C. The enantiomeric excess was determined on a Daicel Chiralpak AD-H column with hexane/2propanol = 98/2, flow = 0.8 mL/min, and detected at a UV wavelength of 254 nm. Retention times: 13.2 min (major), 14.3 min, 67% ee. [α]20D = +44.6 (c 0.454, CH2Cl2). 1H NMR (400 MHz, CDCl3): δ 8.78 (t, J = 7.3 Hz, 2H, ArH), 7.98 (d, J = 9.0 Hz, 1H, ArH), 7.87 (d, J = 7.9 Hz, 2H, ArH), 7.71−7.66 (m, 2H, ArH), 7.64− 7.58 (m, 2H, ArH), 7.44 (d, J = 9.1 Hz, 1H, ArH), 7.39−7.37 (m, 2H, ArH), 7.33−7.27 (m, 2H, ArH), 7.21−7.17 (m, 1H, ArH), 3.74 (s, 3H, OCH3). 13C NMR (100 MHz, CDCl3): δ 154.8, 134.4, 133.3, 132.2, 131.9, 130.6, 130.3, 129.6, 129.14, 129.12, 128.8, 127.9, 126.9, 126.7, 126.6, 126.58, 126.52, 126.4, 125.6, 123.7, 123.2, 122.9, 122.7, 113.9, 56.8. HRMS (positive ESI; m/z): [M + H]+ calcd for C25H19O 335.1436, found 335.1438. (S)-9-(2-Ethoxynaphthalen-1-yl)phenanthrene (9k). White solid (55.7 mg, 80%). Mp: 115−117 °C. The enantiomeric excess was determined on a Daicel Chiralpak AD-H column with hexane/2propanol = 98/2, flow = 0.6 mL/min, and detected at a UV wavelength of 254 nm. Retention times: 15.5 min (major), 16.7 min, 68% ee. [α]20D = +129.2 (c 0.616, CH2Cl2). 1H NMR (400 MHz, CDCl3): δ 8.78 (dd, J = 3.3, 8.3 Hz, 2H, ArH), 7.96 (d, J = 9.0 Hz, 1H, ArH), 7.87 (t, J = 6.7 Hz, 2H, ArH), 7.71−7.67 (m, 2H, ArH), 7.64− 7.60 (m, 2H, ArH), 7.44−7.29 (m, 5H, ArH), 7.23−7.18 (m, 1H, ArH), 4.12−3.98 (m, 2H, OCH2CH3), 1.01 (t, J = 7.0 Hz, 3H, OCH2CH3). 13C NMR (100 MHz, CDCl3): δ 154.1, 134.4, 133.4, 132.2, 132.0, 130.5, 130.3, 129.5, 129.2, 129.1, 128.7, 127.9, 127.0, 126.6, 126.49, 126.46, 126.4, 126.3, 125.7, 124.0, 123.7, 122.8, 122.7, 115.7, 65.3, 15.0. HRMS (positive ESI; m/z): [M + H]+ calcd for C26H21O 349.1592, found 349.1590. (S)-9-(2-(Benzyloxy)naphthalen-1-yl)phenanthrene (9l). White solid (64.0 mg, 78%). Mp: 134−136 °C. The enantiomeric excess was determined on a Daicel Chiralcel OD-H column with hexane/2propanol = 98/2, flow = 0.25 mL/min, and detected at a UV wavelength of 254 nm. Retention times: 44.2 min, 47.0 min (major), 62% ee. [α]20D = +93.6 (c 1.120, CH2Cl2). 1H NMR (400 MHz, CDCl3): δ 8.78 (t, J = 8.1 Hz, 2H, ArH), 7.90 (d, J = 9.0 Hz, 1H, ArH), 7.86−7.83 (m, 2H, ArH), 7.70−7.58 (m, 4H, ArH), 7.43−7.29 (m, 5H, ArH), 7.21−7.17 (m, 1H, ArH), 7.12−7.04 (m, 3H, ArH), 6.93 (d, J = 6.6 Hz, 2H, ArH), 5.06 (d, J = 12.6 Hz, 1H, OCHHC6H5), 5.01 (d, J = 12.6 Hz, 1H, OCHHC6H5). 13C NMR (100 MHz, CDCl3): δ 153.8, 137.2, 134.4, 133.3, 132.2, 132.0, 130.6, 130.4, 129.5, 129.4, 129.3, 128.8, 128.3, 127.9, 127.6, 127.1, 127.0, 126.7, 126.64, 126.60, 126.53, 126.47, 125.7, 124.5, 124.0, 122.9, 122.7, 116.0, 71.4. HRMS (positive ESI; m/z): [M + Na]+ calcd for C31H22NaO 433.1568, found 433.1563. X-ray Diffraction Studies. Crystals of 3c−f (CCDCs 857258, 857257, 857259, 857260) were obtained by recrystallization from CH2Cl2/n-hexane at ambient temperature. Their data were collected on an Oxford diffraction Gemini E diffractometer with graphite203

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Organometallics

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monochromated Mo Kα radiation (λ = 0.71070 Å). The structures were solved by direct methods using the SHELXS-97 program, and all non-hydrogen atoms were refined anisotropically on F2 by the fullmatrix least-squares technique, which used the SHELXL-97 crystallographic software package.25 The hydrogen atoms were included but not refined. Details of the crystal structure determination of the Pd(II) complexes are summarized in Table S1 in the Supporting Information.

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(5) (a) Wu, L.-Y.; Hao, X.-Q.; Xu, Y.-X.; Jia, M.-Q.; Wang, Y.-N.; Gong, J.-F.; Song, M.-P. Organometallics 2009, 28, 3369. (b) Yang, M.J.; Liu, Y.-J.; Gong, J.-F.; Song, M.-P. Organometallics 2011, 30, 3793. (6) (a) Ohara, M.; Nakamura, S.; Shibata, N. Adv. Synth. Catal. 2011, 353, 3385. (b) Hyodo, K.; Nakamura, S.; Shibata, N. Angew. Chem., Int. Ed. 2012, 51, 10337. (c) Hyodo, K.; Kondo, M.; Funahashi, Y.; Nakamura, S. Chem.Eur. J. 2013, 19, 4128. (d) Nakamura, S.; Hyodo, K.; Nakamura, M.; Nakane, D.; Masuda, H. Chem.Eur. J. 2013, 19, 7304. (7) Arai, T.; Oka, I.; Morihata, T.; Awata, A.; Masu, H. Chem.Eur. J. 2013, 19, 1554. (8) (a) Gong, J.-F.; Zhang, Y.-H.; Song, M.-P.; Xu, C. Organometallics 2007, 26, 6487. (b) Zhang, B.-S.; Wang, C.; Gong, J.-F.; Song, M.-P. J. Organomet. Chem. 2009, 694, 2555. (c) Zhang, B.-S.; Wang, W.; Shao, D.-D.; Hao, X.-Q.; Gong, J.-F.; Song, M.-P. Organometallics 2010, 29, 2579. (d) Niu, J.-L.; Chen, Q.-T.; Hao, X.-Q.; Zhao, Q.-X.; Gong, J.-F.; Song, M.-P. Organometallics 2010, 29, 2148. (e) Hou, A.-T.; Liu, Y.-J.; Hao, X.-Q.; Gong, J.-F.; Song, M.-P. J. Organomet. Chem. 2011, 696, 2857. (9) Wang, T.; Hao, X.-Q.; Zhang, X.-X.; Gong, J.-F.; Song, M.-P. Dalton Trans. 2011, 40, 8964. (10) Selected recent publications: (a) Niu, J.-L.; Hao, X.-Q.; Gong, J.F.; Song, M.-P. Dalton Trans. 2011, 40, 5135. (b) Hao, X. -Q.; Niu, J.L.; Zhao, X.-M.; Gong, J.-F.; Song, M.-P. Chin. J. Org. Chem. 2013, 33, 663. (c) Wang, T.; Niu, J.-L.; Liu, S.-L.; Huang, J.-J.; Gong, J.-F.; Song, M.-P. Adv. Synth. Catal. 2013, 355, 927. (d) Wang, T.; Hao, X.-Q.; Huang, J.-J.; Niu, J.-L.; Gong, J.-F.; Song, M.-P. J. Org. Chem. 2013, 78, 8712. (11) Ishihara, M.; Togo, H. Tetrahedron 2007, 63, 1474. (12) (a) Neve, F.; Crispini, A.; Pietro, C. D.; Campagna, S. Organometallics 2002, 21, 3511. (b) Song, D.; Morris, R. H. Organometallics 2004, 23, 4406. (c) Bianchini, C.; Lenoble, G.; Oberhauser, W.; Parisel, S.; Zanobini, F. Eur. J. Inorg. Chem. 2005, 4794. (13) (a) Galliford, C. V.; Scheidt, K. A. Angew. Chem., Int. Ed. 2007, 46, 8748. (b) Trost, B. M.; Brennan, M. K. Synthesis 2009, 3003. (c) Zhou, F.; Liu, Y. L.; Zhou, J. Adv. Synth. Catal. 2010, 352, 1381. (14) (a) Kawasaki, T.; Nagaoka, M.; Satoh, T.; Okamoto, A.; Ukon, R.; Ogawa, A. Tetrahedron 2004, 60, 3493. (b) Kawasaki, T.; Takamiya, W.; Okamoto, N.; Nagaoka, M.; Hirayama, T. Tetrahedron Lett. 2006, 47, 5379. (c) Kitajima, M.; Mori, I.; Arai, K.; Kogure, N.; Takayama, H. Tetrahedron Lett. 2006, 47, 3199. (15) (a) Sano, D.; Nagata, K.; Itoh, T. Org. Lett. 2008, 10, 1593. (b) Yang, Y.; Moinodeen, F.; Chin, W.; Ma, T.; Jiang, Z.; Tan, C.-H. Org. Lett. 2012, 12, 4762. (16) For synthesis of 3-allyl-3-hydroxyoxindoles from isatins, see: (a) Nair, V.; Ros, S.; Jayan, C. N.; Viji, S. Synthesis 2003, 2542. (b) Alcaide, B.; Almendros, P.; Rodríguez-Acebes, R. J. Org. Chem. 2005, 70, 3198. (c) Grant, C. D.; Krische, M. J. Org. Lett. 2009, 11, 4485. (d) Vyas, D. J.; Fröhlich, R.; Oestreich, M. J. Org. Chem. 2010, 75, 6720. For catalytic asymmetric allylation of isatins, see: (e) Qiao, X. C.; Zhu, S. F.; Zhou, Q. L. Tetrahedron: Asymmetry 2009, 20, 1254. (f) Itoh, J.; Han, S. B.; Krische, M. J. Angew. Chem., Int. Ed. 2009, 48, 6313. (g) Cao, Z.-Y.; Zhang, Y.; Ji, C.-B.; Zhou, J. Org. Lett. 2011, 13, 6398. (h) Zheng, K.; Yin, C.; Liu, X.; Lin, L.; Feng, X. Angew. Chem., Int. Ed. 2011, 50, 2573. (i) Hanhan, N. V.; Tang, Y. C.; Tran, N. T.; Franz, A. K. Org. Lett. 2012, 14, 2218. (j) Silverio, D. L.; Torker, S.; Pilyugina, T.; Vieira, E. M.; Snapper, M. L.; Haeffner, F.; Hoveyda, A. H. Nature 2013, 494, 216. (17) (a) Miyaura, N.; Suzuki, A. Chem. Rev. 1995, 95, 2457. (b) Suzuki, A. J. Organomet. Chem. 1999, 576, 147. (c) Kotha, S.; Lahiri, K.; Kashinath, D. Tetrahedron 2002, 58, 9633. (d) Suzuki, A. J. Organomet. Chem. 2002, 653, 83. (e) Bellina, F.; Carpita, A.; Rossi, R. Synthesis 2004, 15, 2419. (f) Alonso, F.; Beletskaya, I. P.; Yus, M. Tetrahedron 2008, 64, 3047. (g) Molander, G. A.; Canturk, B. Angew. Chem., Int. Ed. 2009, 48, 9240. (18) (a) Yin, J.; Buchwald, S. L. J. Am. Chem. Soc. 2000, 122, 12051. (b) Cammidge, A. N.; Crépy, K. V. L Chem. Commun. 2000, 1723. (c) Castanet, A.-S.; Colobert, F.; Broutin, P.-E.; Obringer, M.

ASSOCIATED CONTENT

S Supporting Information *

Crystallographic details for complexes 3c−f. Additional catalytical results on the allylation of a ketimine derived from N-benzylisatin. Proposed reaction mechanisms for the asymmetric allylation of isatins and the Suzuki−Miyaura reaction. Characterization data of the known catalysis products, 1H NMR and 13C NMR spectra of all new compounds 1−3, and 1H or/ and 13C NMR spectra of all catalysis products as well as their chiral HPLC spectra and CIF files for the four pincer Pd complexes including 3c, 3d, 3e·(n-hexane), and (2 × 3f)· CH2Cl2. This material is available free of charge via the Internet at http://pubs.acs.org.

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AUTHOR INFORMATION

Corresponding Authors

*(J.-F. Gong) E-mail: [email protected]. *(M.-P. Song) E-mail: [email protected]. Tel/Fax: (+86)371-6778-3012. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS The authors are grateful to the National Natural Science Foundation of China (21272217), Program for Science &Technology Innovation Talents in Universities of Henan Province (2012HASTIT003), and Key Technologies R & D Program of Henan Province (102101210200) for financial support of this work.

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