Article Cite This: Organometallics XXXX, XXX, XXX−XXX
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Ir-Catalyzed Intermolecular Asymmetric Allylic Alkylation of β‑Tetralones Dong-Song Zheng,† Zheng-Le Zhao,† Qing Gu,* and Shu-Li You* State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Lu, Shanghai 200032, People’s Republic of China
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S Supporting Information *
ABSTRACT: β-Tetralones are useful synthetic intermediates and can act as precursors of β-naphthols. Herein, Ir-catalyzed intermolecular asymmetric alkylation of substituted β-tetralones has been realized. In the presence of an Ir complex, derived from 2 mol % of [Ir(cod)Cl]2 and 4 mol % of the Alexakis ligand, asymmetric allylic alkylation reactions of various β-tetralones and allyl carbonates proceeded smoothly in good to excellent yields with excellent enantioselectivity. The reaction provides an efficient synthesis of highly enantioenriched tetralones and β-naphthols.
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INTRODUCTION Ir-catalyzed asymmetric allylic substitution reactions have been well developed in the last three decades, providing reliable synthesis of chiral allylic stereocenters in high enantioselectivity.1−3 Among the nucleophiles developed, aromatic compounds are found to be compatible ones, and efficient C−C formation results via a Friedel−Crafts type allylic alkylation. However, asymmetric allylic alkylation of phenols and naphthols by forming C−C bonds is challenging since the reaction generally proceeds with O-alkylation, forming a C−O bond (Scheme 1).4 Previous successful examples are mainly
might proceed in high stereoselectivity and the products obtained should be able to be converted to enantioenriched βnaphthols. In this paper, we report our results on Ir-catalyzed asymmetric allylic alkylation of β-tetralones. The interconversion of alkylated β-tetralone product to the corresponding βnaphthol has also been demonstrated.
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RESULTS AND DISCUSSION At the outset of our study, we chose methyl cinnamyl carbonate (2a) as the electrophile to test the allylic substitution reaction of β-tetralone (1a). In the presence of an iridium catalyst prepared from [Ir(cod)Cl]2 (2 mol %) and the (S,S,Sa)-Feringa ligand L1 (4 mol %),9 the allylic alkylation reaction of β-tetralone with t-BuOLi (100 mol %) as the base in CH2Cl2 proceeded smoothly to give a mixture of alkylated diastereoisomers 3a (dr = 1:1). By conversion of the ketone moiety to a silyl enol ether, 3aa was prepared with 90% ee in 73% yield over two steps (Scheme 2). Encouraged by these preliminary results, we further screened a series of chiral phosphoramidite ligands (L2−L6). The results are summarized in Scheme 3. The reaction with the (S,S,Sa)-Alexakis ligand (L2)10 gave 3aa in excellent yield (93%) with slightly increased ee (92%). A trace amount of 3aa was obtained in the presence of L3. The reactions with THQphos (L4) and BHPphos (L5)11 only led to moderate yields and ee values (Scheme 3: L4, 56% yield, 62% ee; L5,
Scheme 1. Asymmetric Allylic Alkylation Reaction of Naphthol and β-Tetralone
based on intramolecular design to overcome the competition of O-alkylation.5,6 There are only sporadic examples of intermolecular C-allylation reactions of naphthols.7 On the other hand, β-tetralones are important synthetic intermediates and can act as the precursors of β-naphthols.8 We envisaged that Ir-catalyzed asymmetric allylic alkylation of β-tetralones © XXXX American Chemical Society
Special Issue: Asymmetric Synthesis Enabled by Organometallic Complexes Received: June 20, 2019
A
DOI: 10.1021/acs.organomet.9b00416 Organometallics XXXX, XXX, XXX−XXX
Article
Organometallics Table 1. Screening of Solvents and Basesa
Scheme 2. Preliminary Attempt of Ir-Catalyzed Asymmetric Allylic Alkylation of β-Tetralone
Scheme 3. Screening of the Ligands
entry
base
solvent
yield/%b
ee/%c
1 2 3 4 5 6 7 8 9 10 11 12
t-BuOLi t-BuOLi t-BuOLi t-BuOLi t-BuOLi t-BuONa t-BuOK (t-BuO)2Mg Cs2CO3 DMAP DABCO none
DCM toluene 1,4-dioxane THF Et2O Et2O Et2O Et2O Et2O Et2O Et2O Et2O
93 64 96 93 97 20/1 [Phenomenex lux 5 μ Cellulose-1 (0.46 cm × 25 cm); methanol/water = 90/10; flow rate 0.7 mL/min; detection wavelength 254 nm; tR = 28.76 (major), 27.10 (minor) min]. [α]D20 = −45.6 (c = 2.5, CHCl3). 1H NMR (300 MHz, CDCl3): δ 7.24−7.19 (m, 2H), 7.08−7.00 (m, 3H), 6.94−6.84 (m, 3H), 6.48−6.35 (m, 1H), 5.29 (d, J = 4.5 Hz, 1H), 5.22 (d, J = 14.4 Hz, 1H), 5.21 (d, J = 12.0 Hz, 1H), 2.96−2.80 (m, 2H), 2.65−2.54 (m, 1H), 2.50−2.40 (m, 3H), 1.86−1.77 (m, 1H), 0.91 (s, 9H), 0.89 (s, 6H), 0.19 (s, 3H), 0.15 (s, 3H). 13C NMR (75 MHz, CDCl3): δ 151.7, 140.1, 139.1, 135.6, 134.1, 129.1, 127.4, 127.1, 126.0, 125.3, 124.4, 116.9, 116.8, 45.3, 45.1, 30.5, 29.8, 29.6, 26.0, 22.7, 22.6, 18.4, −3.1. IR (film): νmax (cm−1) 3061, 2957, 2887, 2859, 1626, 1602, 1507, 1467, 1363, 1336, 1256, 1193, 1159, 1092, 1001, 964, 885, 829, 781, 755, 723, 677. ESIMS (m/z): exact mass calcd for C29H41OSi [M + H]+, 433.2921; found, 433.2919.
Scheme 4. Aromatization of Substituted Tetralone
meric mixture 3a was hydrogenated under 1 atm of H2 in the presence of 10% Pd/C. The aromatization of 4a with TBSOTf (20 mol %) and NBS (100 mol %) then afforded C1-alkylated 2-naphthol 5a in 90% yield and without erosion of enantioselectivity (93% ee).8a The absolute configuration of 5a was assigned as S by comparing the sign of the optical rotation with that of (R)-5a obtained from the known method (for details, see the Supporting Information).7e A proposed mechanism13 as depicted in Scheme 5 starts with the active metallacyclic iridium phosphoramidite catalyst Scheme 5. Proposed Catalytic Cycle
(I) generated from [Ir(COD)Cl]2 and L by nPrNH2 activation. Irreversible anti-nucleophilic attack of β-tetralone on the πallyliridium intermediate (II), which is generated after oxidative addition of the allylic carbonate to I, occurs to afford Ir species III. The final product is obtained with regeneration of the active species after dissociation to finish the catalytic cycle. This alkylation is considered to be an “outersphere” process, since the absolute configuration of the product is consistent with the mechanism proposed by Hartwig and co-workers.13c
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CONCLUSION In summary, we have developed an efficient iridium-catalyzed intermolecular asymmetric allylic alkylation reaction of βtetralones under mild conditions. The reaction displays rather general substrate scope and tolerates a variety of functional groups. The tetralone moiety in the product can be further oxidized to naphthol without affecting the enantioselectivity of the stereocenter. Therefore, the method here offers an alternative route for Friedel−Crafts type allylic alkylation of β-naphthols.
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EXPERIMENTAL SECTION
General Procedure for Ir-Catalyzed Intermolecular Asymmetric Allylic Alkylation of β-Tetralone. A flame-dried Schlenk tube was cooled to room temperature and filled with argon. In this flask were placed [Ir(cod)Cl]2 (5.7 mg, 0.01 mmol, 2 mol %), C
DOI: 10.1021/acs.organomet.9b00416 Organometallics XXXX, XXX, XXX−XXX
Article
Organometallics Compound (S)-3ad: colorless oil, 192.3 mg, 93% yield, 96% ee. b/l > 20/1 [Phenomenex lux 5 μ Cellulose-1 (0.46 cm × 25 cm); methanol/water = 90/10; flow rate 0.7 mL/min; detection wavelength 254 nm; tR = 22.94 (major), 20.37 (minor) min]. [α]D20 = −66.5 (c = 2.0, CHCl3). 1H NMR (400 MHz, CDCl3): δ 7.25−7.20 (m, 4H), 7.08−7.06 (m, 1H), 6.96−6.89 (m, 2H), 6.78 (dd, J = 7.2, 2.0 Hz, 1H), 6.41−6.32 (m, 1H), 5.26−5.18 (m, 3H), 2.96−2.80 (m, 2H), 2.60−2.39 (m, 2H), 0.88 (s, 9H), 0.18 (s, 3H), 0.13 (s, 3H). 13C NMR (75 MHz, CDCl3): δ 152.1, 141.6, 138.3, 135.1, 134.0, 131.6, 129.1, 128.5, 127.2, 126.0, 125.0, 124.6, 117.7, 116.2, 44.8, 29.7, 29.5, 26.0, 25.9, 18.4, −3.1, −3.1. IR (film): νmax (cm−1) 3415, 3068, 3024, 2952, 2928, 2856, 1710, 1635, 1596, 1490, 1405, 1326, 1258, 1164, 1091, 1014, 968, 922, 832, 747, 643. ESI-MS (m/z): exact mass calcd for C25H32OClSi [M + H]+, 411.1905; found, 411.1905. Compound (S)-3ae: colorless oil, 216.4 mg, 95% yield, 96% ee. b/l > 20/1 [Daicel Chiralcel OD-H (0.46 cm × 25 cm); CO2/2-propanol = 92/8; flow rate 1.3 mL/min; detection wavelength 230 nm; tR = 9.75 (major), 9.34 (minor) min]. [α]D20 = −84.9 (c = 0.5, CHCl3). 1 H NMR (300 MHz, CDCl3): δ 7.36 (d, J = 8.4 Hz, 2H), 7.18 (d, J = 8.7 Hz, 2H), 7.08−7.05 (m, 1H), 6.96−6.90 (m, 2H), 6.80−6.76 (m, 1H), 6.43−6.30 (m, 1H), 5.24−5.17 (m, 3H), 2.98−2.80 (m, 2H), 2.61−2.37 (m, 2H), 0.88 (s, 9H), 0.18 (s, 3H), 0.14 (s, 3H). 13C NMR (75 MHz, CDCl3): δ 152.1, 142.2, 138.2, 135.1, 134.1, 131.4, 129.6, 127.3, 126.1, 125.0, 124.6, 119.8, 117.8, 116.2, 44.9, 29.8, 29.5, 26.0, 18.5, −3.0, −3.0. IR (film): νmax (cm−1) 3072, 3019, 2954, 2931, 2888, 2858, 1626, 1568, 1485, 1468, 1362, 1335, 1257, 1195, 1160, 1074, 1005, 968, 917, 892, 823, 781, 759, 723, 676. ESI-MS (m/z): exact mass calcd for C25H32BrOSi [M + H]+, 455.1400; found, 455.1401. Compound (S)-3af: colorless oil, 215.5 mg, 97% yield, 95% ee. b/l > 20/1 [Daicel Chiralpak OD-H (0.46 cm × 25 cm); CO2/2propanol = 98/2; flow rate 1.3 mL/min; detection wavelength 214 nm; tR = 10.98 (major), 10.31 (minor) min]. [α]D20 = −52.2 (c = 0.5, CHCl3). 1H NMR (300 MHz, CDCl3): δ 7.56 (d, J = 8.7 Hz, 2H), 7.48 (d, J = 8.1 Hz, 2H), 7.10−7.06 (m, 1H), 6.95−6.91 (m, 2H), 6.79−6.75 (m, 1H), 6.46−6.34 (m, 1H), 5.37 (d, J = 7.8 Hz, 1H), 5.31 (d, J = 9.0 Hz, 1H), 5.29 (d, J = 18.9 Hz, 1H), 3.00−2.82 (m, 2H), 2.63−2.42 (m, 2H), 0.87 (s, 9H), 0.18 (s, 3H), 0.15 (s, 3H). 13C NMR (75 MHz, CDCl3): δ 152.3, 147.5, 147.5, 137.8, 135.1, 134.0, 128.2 (q, J = 32.3 Hz), 128.0, 127.3, 126.1, 125.4 (q, J = 3.7 Hz), 124.7 (q, J = 7.4 Hz), 124.7 (q, J = 270.5 Hz), 118.1, 116.0, 45.4, 30.0, 29.5, 25.9, 18.4, −3.0, −3.1. 19F NMR (282 MHz): δ −62.5. IR (film): νmax (cm−1) 3068, 2954, 2934, 2891, 2861, 1622, 1566, 1486, 1411, 1364, 1327, 1258, 1198, 1158, 1118, 1067, 1004, 971, 920, 894, 824, 775, 757, 720, 672, 620. ESI-MS (m/z): exact mass calcd for C26H32F3OSi [M + H]+, 445.2169; found, 445.2168. Compound (S)-3ag: colorless, 188.7 mg, 96% yield, 93% ee. b/l > 20/1 [Phenomenex lux 5 μ Cellulose-1 (0.46 cm × 25 cm); methol/ water = 90/10; flow rate 0.7 mL/min; detection wavelength 254 nm; tR = 17.77 (major), 16.04 (minor) min]. [α]D20 = −44.4 (c = 2.0, CHCl3). 1H NMR (300 MHz, CDCl3): δ 7.24−7.16 (m, 1H), 7.11− 7.01 (m, 3H), 6.94−6.91 (m, 2H), 6.86−6.81 (m, 2H), 6.45−6.32 (m, 1H), 5.29−5.19 (m, 3H), 2.98−2.78 (m, 2H), 2.62−2.37 (m, 2H), 0.88 (s, 9H), 0.18 (s, 3H), 0.15 (s, 3H). 13C NMR (75 MHz, CDCl3): δ 163.4 (d, J = 242.9 Hz), 152.1, 146.1 (d, J = 6.9 Hz), 138.1, 135.2, 134.1, 129.8 (d, J = 8.1 Hz), 127.3, 126.1, 124.9, 124.6, 123.3 (d, J = 2.8 Hz), 117.9, 116.2, 114.7 (d, J = 21.9 Hz), 112.8 (d, J = 21.3 Hz), 45.3, 29.8, 29.5, 26.0, 18.5, −2.9, −3.0. 19F NMR (282 MHz): δ −114.2 (m). IR (film): νmax (cm−1) 2954, 2931, 2889, 2857, 1627, 1587, 1485, 1468, 1444, 1363, 1257, 1197, 1069, 1002, 983, 867, 832, 778, 754, 683. ESI-MS (m/z): exact mass calcd for C25H32FOSi [M + H]+, 395.2201; found, 395.2204. Compound (S)-3ah: colorless oil, 188.9 mg, 91% yield, 98% ee. b/l > 20/1 [Daicel Chiralcel OD-H (0.46 cm × 25 cm); CO2/2-propanol = 97/3; flow rate 1.3 mL/min; detection wavelength 230 nm; tR = 12.05 (major), 12.97 (minor) min]. [α]D20 = −50.8 (c = 1.0, CHCl3). 1 H NMR (400 MHz, CDCl3): δ 7.31 (s, 1H), 7.18−7.07 (m, 4H), 6.97−6.91 (m, 2H), 6.81−6.79 (m, 1H), 6.42−6.33 (m, 1H), 5.24− 5.19 (m, 3H), 2.97−2.80 (m, 2H), 2.61−2.39 (m, 2H), 0.88 (s, 9H), 0.18 (s, 3H), 0.15 (s, 3H). 13C NMR (75 MHz, CDCl3): δ 152.2,
145.5, 138.1, 135.3, 134.5, 134.1, 129.8, 127.9, 127.4, 126.3, 126.3, 126.0, 124.9, 124.8, 118.0, 116.2, 45.4, 29.9, 29.6, 26.2, 26.1, 18.5, −2.8, −2.9. IR (film): νmax (cm−1) 3066, 3018, 2953, 2931, 2888, 2858, 1626, 1594, 1569, 1470, 1422, 1362, 1335, 1256, 1193, 1160, 1090, 1002, 968, 917, 829, 780, 761, 735, 679. ESI-MS (m/z): exact mass calcd for C25H32ClOSi [M + H]+, 411.1905; found, 411.1901. Compound (S)-3ai: colorless oil, 213.1 mg, 94% yield, 95% ee. b/l > 20/1 [Daicel Chiralpak AD-H (0.46 cm × 25 cm); CO2/2-propanol = 95/5; flow rate 1.3 mL/min; detection wavelength 230 nm; tR = 5.80 (major), 6.25 (minor) min]. [α]D20 = −58.8 (c = 1.0, CHCl3). 1 H NMR (300 MHz, CDCl3): δ 7.48 (s, 1H), 7.29−7.18 (m, 2H), 7.12−7.05 (m, 2H), 6.95−6.91 (m, 2H), 6.82−6.78 (m, 1H), 6.43− 6.31 (m, 1H), 5.25−5.18 (m, 3H), 2.98−2.77 (m, 2H), 2.62−2.37 (m, 2H), 0.87 (s, 9H), 0.17 (s, 3H), 0.15 (s, 3H). 13C NMR (75 MHz, CDCl3): δ 152.2, 145.8, 138.0, 135.2, 134.0, 130.7, 130.0, 129.1, 127.3, 126.4, 126.2, 124.8, 124.7, 122.9, 118.0, 116.0, 45.4, 29.8, 29.5, 26.0, 18.5, −2.9, −3.0. IR (film): νmax (cm−1) 3065, 3017, 2954, 2931, 2888, 2857, 1626, 1592, 1566, 1469, 1419, 1362, 1335, 1256, 1193, 1073, 1002, 968, 897, 809, 779, 759, 724, 677. ESI-MS (m/z): exact mass calcd for C25H32BrOSi [M + H]+, 455.1400; found, 455.1396. Compound (S)-3aj: colorless oil, 209.2 mg, 94% yield, 95% ee. b/l > 20/1 [Phenomenex lux 5 μ Cellulose-1 (0.46 cm × 25 cm); methol/water = 90/10; flow rate 0.7 mL/min; detection wavelength 254 nm; tR = 17.60 (major), 15.86 (minor) min]. [α]D20 = −73.5 (c = 2.0, CHCl3). 1H NMR (300 MHz, CDCl3): δ 7.60 (s, 1H), 7.50−7.31 (m, 3H), 7.10−7.07 (m, 1H), 6.96−6.92 (m, 2H), 6.81−6.78 (m, 1H), 6.47−6.34 (m, 1H), 5.28−5.21 (m, 3H), 2.96−2.81 (m, 2H), 2.63−2.41 (m, 2H), 0.85 (s, 9H), 0.16 (s, 3H), 0.14 (s, 3H). 13C NMR (75 MHz, CDCl3): δ 152.3, 144.3, 137.8, 135.3, 134.0, 131.1, 131.1, 130.7 (q, J = 31.7 Hz), 128.8, 127.3, 126.2, 124.6 (q, J = 6.9 Hz), 124.6 (q, J = 275.7 Hz), 124.4 (q, J = 4.1 Hz), 122.9 (q, J = 3.5 Hz), 118.1, 115.8, 45.5, 29.7, 29.5, 25.9, 18.4, −3.1, −3.1. 19F NMR (282 MHz): δ −62.7. IR (film): νmax (cm−1) 3066, 2950, 2933, 2884, 2859, 2831, 1626, 1568, 1487, 1438, 1361, 1326, 1260, 1194, 1161, 1120, 1076, 1028, 1000, 967, 927, 901, 822, 775, 754, 723, 697, 674. ESI-MS (m/z): exact mass calcd for C26H32F3OSi [M + H]+, 445.2169; found, 445.2164. Compound (S)-3ak: colorless oil, 143.9 mg, 75% yield, 93% ee. b/l > 20/1 [Daicel Chiralcel OD-H (0.46 cm × 25 cm); CO2/2-propanol = 95/5; flow rate 1.3 mL/min; detection wavelength 230 nm; tR = 9.74 (major), 10.28 (minor) min]. [α]D20 = −22.2 (c = 2.0, CHCl3). 1 H NMR (400 MHz, CDCl3): δ 7.11−7.06 (m, 2H), 7.01−6.89 (m, 4H), 6.82−6.81 (m, 1H), 6.50−6.41 (m, 1H), 5.44 (d, J = 7.2 Hz, 1H), 5.24 (d, J = 16.8 Hz, 1H), 5.19(d, J = 10.0 Hz, 1H), 2.94−2.80 (m, 2H), 2.57−2.39 (m, 2H), 0.92 (s, 9H), 0.19 (s, 3H), 0.18 (s, 3H). 13 C NMR (100 MHz, CDCl3): δ 151.6, 148.1, 138.1, 134.8, 133.7, 126.9, 126.6, 125.7, 124.8, 124.3, 123.7, 123.4, 116.7, 116.4, 41.5, 29.5, 29.2, 25.7, 18.2, −3.4. IR (film): νmax (cm−1) 3071, 2954, 2931, 2888, 2857, 1626, 1568, 1486, 1467, 1363, 1335, 1256, 1194, 1160, 1003, 968, 917, 882, 830, 780, 758, 692. ESI-MS (m/z): exact mass calcd for C23H31OSSi [M + H]+, 383.1859; found, 383.1859. Compound (S)-3al: colorless oil, 91.0 mg, 58% yield, 88% ee. b/l > 20/1 [Daicel Chiralcel OJ-RH (0.46 cm × 15 cm); 20 mM HCOONH4 (aq) /MeOH = 20/80; flow rate 0.9 mL/min; detection wavelength 220 nm; tR = 23.66 (major), 31.65 (minor) min]. [α]D20 = 44.1 (c = 2.0, CHCl3). 1H NMR (400 MHz, CDCl3): δ 7.31 (d, J = 5.7 Hz, 1H), 7.10−7.06 (m, 2H), 6.97 (t, J = 5.7 Hz, 1H), 6.14−6.06 (m, 1H), 5.08 (d, J = 18.0 Hz, 1H), 5.08 (d, J = 10.8 Hz, 1H), 4.10− 4.04 (m, 1H), 2.47−2.38 (m, 1H), 2.36−2.27 (m, 1H), 1.35 (d, J = 7.2 Hz, 3H), 0.97 (s, 9H), 0.20 (s, 3H), 0.19 (s, 3H). 13C NMR (100 MHz, CDCl3): δ 150.0, 143.4, 135.7, 134.0, 126.9, 125.7, 124.3, 124.1, 118.4, 112.7, 33.2, 29.5, 29.4, 25.8, 18.2, 17.1, −3.4, −3.5. IR (film): νmax (cm−1) 3077, 2957, 2932, 2888, 2858, 1627, 1568, 1486, 1362, 1335, 1256, 1192, 1158, 1084, 1041, 1001, 952, 907, 838, 810, 780, 728, 677. ESI-MS (m/z): exact mass calcd for C20H31OSi [M + H]+, 315.2139; found, 315.2146. Compound (S)-3ba: colorless oil, 166.9 mg, 85% yield, 96% ee. b/l > 20/1 [Phenomenex lux 5 μ Cellulose-3 (0.46 cm × 25 cm); acetonitrile/water = 60/40; flow rate 0.7 mL/min; detection D
DOI: 10.1021/acs.organomet.9b00416 Organometallics XXXX, XXX, XXX−XXX
Article
Organometallics wavelength 254 nm; tR = 27.42 (major), 24.94 (minor) min]. [α]D20 = −85.2 (c = 1.0, CHCl3). 1H NMR (400 MHz, CDCl3): δ 7.31−7.24 (m, 5H), 7.18−7.13 (m, 1H), 6.79−6.74 (m, 2H), 6.60−6.55 (m, 1H), 6.42−6.34 (m, 1H), 5.32 (d, J = 7.6 Hz, 1H), 5.24−5.17 (m, 2H), 2.94−2.78 (m, 2H), 2.59−2.39 (m, 2H), 0.89 (s, 9H), 0.18 (s, 3H), 0.14 (s, 3H). 13C NMR (75 MHz, CDCl3): δ 160.2 (d, J = 241.9 Hz), 151.0, 142.8, 138.5, 136.4 (d, J = 6.8 Hz), 131.2, 128.5, 127.7, 126.4 (d, J = 7.4 Hz), 126.0, 117.4, 116.1, 114.3 (d, J = 21.1 Hz), 112.3 (d, J = 20.6 Hz), 45.1, 29.6, 29.5, 26.0, 18.4, −3.0, −3.1. 19F NMR (376 MHz): δ −119.3. IR (film): νmax (cm−1) 3080, 3061, 3027, 2954, 2932, 2889, 2858, 1629, 1606, 1584, 1494, 1468, 1358, 1329, 1253, 1195, 1146, 1110, 1006, 974, 918, 887, 838, 780, 728, 699, 669. ESI-MS (m/z): exact mass calcd for C25H32FOSi [M + H]+, 395.2201; found, 395.2212. Compound (S)-3ca: colorless oil, 182.2 mg, 88% yield, 94% ee. b/l > 20/1 [Phenomenex lux 5 μ Cellulose-3 (0.46 cm × 25 cm); acetonitrile/water = 85/15; flow rate 0.7 mL/min; detection wavelength 254 nm; tR = 6.90 (major), 6.34 (minor) min]. [α]D20 = −66.5 (c = 1.0, CHCl3). 1H NMR (400 MHz, CDCl3): δ 7.29−7.23 (m, 5H), 7.18−7.13 (m, 1H), 7.03 (d, J = 2.4 Hz, 1H), 6.84 (dd, J = 8.4, 2.4 Hz, 1H), 6.73 (d, J = 8.4 Hz, 1H), 6.41−6.33 (m, 1H), 5.31 (d, J = 7.6 Hz, 1H), 5.22 (d, J = 10.0 Hz, 1H), 5.18 (d, J = 16.8 Hz, 1H), 2.93−2.78 (m, 2H), 2.58−2.40 (m, 2H), 0.89 (s, 9H), 0.18 (s, 3H), 0.14 (s, 3H). 13C NMR (75 MHz, CDCl3): δ 152.0, 142.7, 138.3, 136.0, 133.9, 129.6, 128.5, 127.7 127.1, 126.4, 126.0, 125.9, 117.5, 116.1, 45.0, 29.5, 29.3, 26.0, 18.4, −3.1. IR (film): νmax (cm−1) 3060, 3025, 2954, 2931, 2888, 2856, 1620, 1597, 1487, 1469, 1358, 1330, 1247, 1200, 1124, 1097, 1030, 1003, 973, 919, 895, 838, 816, 775, 743, 694, 655. ESI-MS (m/z): exact mass calcd for C25H32ClOSi [M + H]+, 411.1905; found, 411.1922. Compound (S)-3da: colorless oil, 182.8 mg, 81% yield, 97% ee. b/l > 20/1 [Phenomenex lux 5 μ Cellulose-3 (0.46 cm × 25 cm); acetonitrile/water = 85/15; flow rate 0.7 mL/min; detection wavelength 254 nm; tR = 7.48 (major), 6.67 (minor) min]. [α]D20 = −60.0 (c = 2.0, CHCl3). 1H NMR (400 MHz, CDCl3): δ 7.29−7.23 (m, 5H), 7.19−7.14 (m, 2H), 6.99 (dd, J = 8.4, 2.4 Hz, 1H), 6.68 (d, J = 8.4 Hz, 1H), 6.41−6.32 (m, 1H), 5.31 (d, J = 7.6 Hz, 1H), 5.22 (d, J = 10.0 Hz, 1H), 5.18 (d, J = 17.2 Hz, 1H), 2.93−2.78 (m, 2H), 2.57−2.39 (m, 2H), 0.87 (s, 9H), 0.18 (s, 3H), 0.14 (s, 3H). 13C NMR (75 MHz, CDCl3): δ 152.2, 142.6, 138.2, 136.3, 134.4, 129.9, 128.8, 128.5, 127.6, 126.7, 126.0, 117.7, 117.5, 116.2, 44.9, 29.5, 29.2, 25.9, 18.4, −3.1. IR (film): v max (cm−1) = 3062, 2954, 2932, 2889, 2858, 1620, 1598, 1486, 1470, 1358, 1328, 1257, 1201, 1123, 1085, 1032, 1003, 972, 918, 892, 838, 806, 775, 745, 723, 695, 677, 646. ESI-MS (m/z): exact mass calcd for C25H32BrOSi [M + H]+, 455.1400; found, 455.1406. Compound (S)-3ea: colorless oil, 177.6 mg, 88% yield, 96% ee. b/l > 20/1 [Phenomenex lux 5 μ Cellulose-1 (0.46 cm × 25 cm); acetonitrile/water = 90/10; flow rate 0.7 mL/min; detection wavelength 214 nm; tR = 7.48 (major), 6.67 (minor) min]. [α]D20 = −81.1 (c = 0.5, CHCl3). 1H NMR (400 MHz, CDCl3): δ 7.31−7.29 (m, 2H), 7.26−7.22 (m, 2H), 7.16−7.11 (m, 1H), 6.86 (t, J = 8.4 Hz, 1H), 6.57 (d, J = 8.0 Hz, 1H), 6.51 (d, J = 8.0 Hz, 1H), 6.46−6.36 (m, 1H), 5.30 (d, J = 7.6 Hz, 1H), 5.25−5.22 (m, 1H), 5.21−5.20 (m, 1H), 3.78 (s, 3H), 3.04−2.96 (m, 1H), 2.86−2.76 (m, 1H), 2.56− 2.36 (m, 2H), 0.88 (s, 9H), 0.17 (s, 3H), 0.13 (s, 3H). 13C NMR (100 MHz, CDCl3): δ 155.7, 151.8, 143.0, 138.7, 136.6, 128.1, 127.4, 125.9, 125.5, 121.5, 118.3, 116.9, 116.2, 107.2, 55.4, 45.1, 29.0, 25.7, 21.0, 18.2, −3.3, −3.4. IR (film): νmax (cm−1) 2951, 2929, 2887, 2856, 1627, 1596, 1468, 1360, 1256, 1212, 1194, 1033, 1002, 914, 852, 836, 811, 780, 737, 718, 697, 681. ESI-MS (m/z): exact mass calcd for C26H35O2Si [M + H]+, 407.2401; found, 407.2403. Procedure for Aromatization of Allylic-Substituted Tetralone. To a diastereoisomeric mixture of 3a (1.35 g, 5.15 mmol) in methanol (20 mL) was added 10% Pd/C (0.30 g). Then the reaction flask was charged with 1 atm of hydrogen. The reaction mixture was stirred at room temperature until the starting material disappeared (monitored by TLC). The crude reaction mixture was filtered with Celite and washed with EtOAc (20 mL, three times). The solvents were removed under reduced pressure. Then the residue was purified
by silica gel column chromatography (PE/EtOAc = 20/1 to 10/1) to afford 4a (1.31 g, 95% yield). In a dried flask were placed 4a (131.0 mg, 0.5 mmol) and CH3CN (20 mL), and then NBS (89.0 mg, 0.5 mmol, 1 equiv) and TBSOTf (27 mg, 0.2 equiv) were added in the dark. The reaction mixture was stirred at room temperature. After the reaction was complete (monitored by TLC), it was quenched by brine (0.5 mL). The organic solvents were removed under reduced pressure. After the mixture was extracted with EtOAc (10 mL, three times), the combined organic layers were dried over anhydrous Na2SO4 and then filtered. The solvent was removed under reduced pressure, and the residue was purified by silica gel column chromatography (PE/EtOAc = 100/1 to 50/1) to afford 5a. Compound (S)-5a: colorless oil, 118.0 mg, 90% yield, 93% ee [Daicel Chiralpak AD-H (0.46 cm × 25 cm); n-hexane/2-propanol = 97/3; flow rate 0.6 mL/min; detection wavelength 230 nm; tR = 21.66 (major), 24.57 (minor) min]. [α]D20 = −154.3 (c = 3.0, CHCl3). 1H NMR (400 MHz, CDCl3): δ 8.07 (d, J = 8.7 Hz, 1H), 7.77 (d, J = 8.1 Hz, 1H), 7.65 (d, J = 9.0 Hz, 1H), 7.39 (dt, J = 1.2, 6.6 Hz, 1H), 7.46−7.17 (m, 7H), 6.98 (d, J = 8.7 Hz, 1H), 4.93−4.99 (m, 1H), 2.39−2.53 (m, 1H), 2.20−2.35 (m, 1H), 0.90 (t, J = 7.5 Hz, 3H). 13C NMR (75 MHz, CDCl3): δ 152.0, 143.7, 134.1, 129.9, 129.1, 129.1, 129.0, 127.8, 126.8, 126.7, 123.5, 123.3, 122.7, 119.4, 42.4, 24.6, 13.0. IR (film): νmax (cm−1) 3536, 3507, 3482, 3454, 3057, 3026, 2964, 2933, 2872, 1948, 1703, 1622, 1600, 1513, 1452, 1390, 1249, 1201, 1147, 1028, 947, 862, 807, 747, 701, 620; EI-MS (m/z): exact mass calcd for C19H18O [M]+, 262.1358; found, 262.1356.
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ASSOCIATED CONTENT
S Supporting Information *
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.organomet.9b00416. Experimental procedures and analysis data for all new compounds (PDF)
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AUTHOR INFORMATION
Corresponding Authors
*E-mail for Q.G.:
[email protected]. *E-mail for S.-L.Y.:
[email protected]. ORCID
Qing Gu: 0000-0003-4963-2271 Shu-Li You: 0000-0003-4586-8359 Author Contributions †
D.-S.Z. and Z.-L.Z. contributed equally to this work.
Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS We thank the National Key R&D Program of China (2016YFA0202900), the National Natural Science Foundation of China (21821002, 21572252), and the CAS (XDB20000000, QYZDY-SSW-SLH012) for generous financial support.
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REFERENCES
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DOI: 10.1021/acs.organomet.9b00416 Organometallics XXXX, XXX, XXX−XXX
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DOI: 10.1021/acs.organomet.9b00416 Organometallics XXXX, XXX, XXX−XXX