H for P−S−C Bond Formation - ACS Publications - American Chemical

Jan 9, 2018 - ABSTRACT: A considerably improved method for the Cu-catalyzed coupling of sulfuryl chloride with P(O)−H was described...
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Cite This: J. Org. Chem. 2018, 83, 1532−1537

Cu(II)/Proline-Catalyzed Reductive Coupling of Sulfuryl Chloride and P(O)−H for P−S−C Bond Formation Xinghua Zhang,* Dungai Wang, Duo An, Boshi Han, Xiang Song, Liang Li, Gaoqi Zhang, and Lixian Wang* School of Chemical and Environmental Engineering, Shanghai Institute of Technology, 100 Hai-Quan Road, Shanghai 201418, China S Supporting Information *

ABSTRACT: A considerably improved method for the Cu-catalyzed coupling of sulfuryl chloride with P(O)−H was described. Using commercially available L-proline as the ligand decreased the precatalyst loading, broadened the substrate scope and greatly promoted the efficiency of the coupling reaction. Moreover, gram-scale preparation, easy-to handle and recyclable catalyst featured this transformation.

C

further extend the scope to new substrates. In particular, the development of reusability of the catalyst, simple workup and mild reaction condition remains a formidable challenge. Herein, we wish to disclose a considerably improved method for the synthesis of (S)-aryl/alkyl phosphinothioates and phosphorothioates based on copper-catalyzed coupling of aryl/alkyl sulfonyl chlorides with P(O)−H (Scheme 1, eq 2). The reaction conditions allowed the use of 4.0 equiv of P(O)− H compounds in excess. Moreover, using commercially available L-proline as the ligand greatly promoted the efficiency of the coupling reaction, and a variety of P(O)−H coupled readily with sulfonyl chlorides under relatively mild conditions. In this respect, our recent finding of ligand-promoted Cucatalyzed coupling reactions has significantly expanded the substrate scope. Initially, we chose tosyl chloride (1a) and P(O)−H, O-ethyl phenylphosphinate (2a), as the model substrates. The influences of different solvents, copper source, ligands, reactant molar ratio, and reaction temperature were screened to explore the optimized condition. As shown in Table 1, Desired coupling product 3a was obtained in 19% yield if the reaction mixture of 1a (0.5 mmol) and 2a (2.0 mmol) was stirred in CH3CN at 80 °C for 3 h (Table 1, entry 1). As expected, the yield of corresponding product 3a increased obviously in the presence of copper salts as catalyst (see the Supporting Information). A series of copper salts and the amount of the catalyst loading were investigated under similar conditions, and the results showed that CuCl2·2H2O (5 mol %) was optimal (57% yield; Table 1, entry 2). Further investigations revealed that the choice of a suitable ligand was the key factor increasing the reaction efficiency, a promising yield of 75% was obtained if the ligand, L-proline (10 mol %), was added, which is more

ompared with the traditional copper-mediated C−C and C−heteroatom bond formation, increased activity and broadened substrate scope have been achieved by using ligandpromoted cross-coupling strategy.1 The enhanced solubility and stability of copper complexes due to the use of these auxiliary ligands was the key to accelerate these transformations. Recently, some amino acide promoted,1a,2 Cucatalyzed C−X coupling have been disclosed and caught more and more attention (Scheme 1, eq 1).2a−e Scheme 1. L-Proline Promoted Cu-Catalyzed C−X Bond Formation

The P−S−C bond is also an important scaffold that have received much attention within the biology and chemistry community.3 Among the existing methods for construction of P−S−C bond,4−6 Cu-catalyzed coupling reactions of sulfonyl chlorides with P(O)−H have become more and more attractive,4d mainly because the coupling partners are readily commercially available, and the reaction could proceed under base-free condition. At the same time, avoiding use of foulsmelling materials, such as aryl-SH and alkyl-SH, is also accord with the increased environmental requirements. Although significant advances have been made in this transformation,6d further improvements are still desirable. For example, how to reduce the loading of the catalyst or P(O)−H reagent and © 2018 American Chemical Society

Received: October 13, 2017 Published: January 9, 2018 1532

DOI: 10.1021/acs.joc.7b02608 J. Org. Chem. 2018, 83, 1532−1537

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The Journal of Organic Chemistry Table 1. Optimization of Reaction Conditiona

Table 2. Reaction of 1 and 2 under Standard Conditionsa

entry

catalyst

ligand

solvent

yield (%)b

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

none CuCl2·2H2O CuCl2·2H2O CuCl2·2H2O CuCl2·2H2O CuCl2·2H2O CuCl2·2H2O CuCl2·2H2O CuCl2·2H2O CuCl2·2H2O CuCl2·2H2O CuCl2·2H2O CuCl2·2H2O CuCl2·2H2O CuCl2·2H2O CuCl2·2H2O

none none L-pro DMAP py bpy 1,10-phen TMEDA L-pro L-pro L-pro L-pro L-pro L-pro L-pro L-pro

CH3CN CH3CN CH3CN CH3CN CH3CN CH3CN CH3CN CH3CN dioxane THF toluene THF dioxane THF THF THF

19 57 75 52 70 32 19 64 72 78 72 27c 66d 74e 89f 69g

a Reaction conditions: 1a (0.5 mmol), 2a (2.0 mmol), catalyst (0.025 mmol), ligand (0.05 mmol), solvent (1.5 mL), 80 °C, under air, 3 h. b Isolated yields based on 1a. c50 °C. d100 °C. eTHF (0.5 mL). fTHF (1.0 mL). gTHF (2.0 mL).

efficient than anyother nitrogen ligands, including pyridine (py), bipyridine (bpy), phenanthroline (1,10-phen), and tetramethylethylenediamine (TMEDA) (Table 1, entries 3− 8). The coupling reaction also proceeded smoothly in other solvents, such as toluene, dioxane, and THF, and THF was the ideal solvent (78% yield; Table 1, entry 10). Unfortunately, the P−S−C bond transformation was not accelerated by elevating the reaction temperature to 100 °C (66% yield; Table 1, entry 13) or reducing it to 50 °C (27% yield; Table 1, entry 12). Interestingly, using 1.0 mL of THF as solvent provided 3a in a 89% yield (Table 1, entry 15) as opposed to 69 or 74% (Table 1, entries 14 and 16) employing 0.5 and 2.0 mL of THF, respectively. These results indicated that the efficiency of the coupling should be controlled by the reactant concentration. Therefore, the optimum reaction conditions were set as 1a (0.5 mmol) and 2a (2.0 mmol) in the presence of CuCl2·2H2O (5 mol %) in THF (1.0 mL), promoted by L-proline (10 mol %), at 80 °C for 3 h (Table 1, entry 15). Next, we conducted a survey of the reaction scope, and the results are summarized in Table 2. A variety of sulfonyl chlorides readily coupled with P(O)−H compound, O-ethyl phenylphosphinate (2a), under the relatively mild reaction condition to produce the corresponding phosphinothioates 3 in good to excellent yields. For para-substituted aryl sulfonyl chlorides, both electron-rich (with methyl, tert-butyl, or methoxyl group) and -deficient (chloro-, bromo-, or trifluoromethyl group) substrates worked well, providing aryl phosphinothioates 3a−3f in 74−90% yields. Morever, this method also can be applied to gram-scale preparation, O-ethyl (S)-(p-tolyl) phenylphosphonothioate, 3a was successfully achieved in 86% yield (Table 2, 1.25 g, 5 mmol). As for the sterically hindered substrate, the ortho-substituted steric hindrance did not significantly affect the reaction efficiency, corresponding product 3g was obtained in 82% yield from 2,4,6-trimethylphenyl sulfonyl chloride (Table 2, 3g). To our delight, the present method is also suitable for 2-naphthalene-

Reaction conditions: 1 (0.5 mmol), 2 (2.0 mmol), CuCl2·2H2O (5 mol %), L-proline (10 mol %), THF(1.0 mL), 80 °C, air, 3 h. Isolated yields based on 1. bReaction conditions: 12 h. a

sulfonyl chloride and 2-thiophenesulfonyl chloride, leading to the desired products 3h and 3i in 88 and 77% yield, respectively (Table 2, 3h and 3i). Notably, under the current reaction condition, the alkyl sulfonyl chlorides could be readily transformed to the corresponding alkyl phosphinothioates 3j−3l in 52−83% yield (Table 2, 3j−3l), further expanding the substrate scope of this approach. The steric hindrance of P(O)−H compound, such as isopropyl phenylphosphinate (2b), DOPO (2c), were also suitable substrates and did not 1533

DOI: 10.1021/acs.joc.7b02608 J. Org. Chem. 2018, 83, 1532−1537

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The Journal of Organic Chemistry significantly affect this transformation, afforded the desired (S)aryl or -alkyl phosphinothioates 3m-3t in 77−92% yield (Table 2, 3m−3t), respectively. Moreover, the configuration of compound 3s was clearly identified by X-ray diffraction (See Supporting Information). It is worth noting that our previous protocol was not applicable to the synthesis of compound 3r;6d however, it could be achieved in 89% yield under the current reaction condition (Table 2, 3r). Similarly, by using the present Pro/Cu-catalyzed coupling strategy, compound 3t was synthesized in high yield (81%; Table 2, 3t), which is enhanced from 32% under the previous method for the coupling of 1butanesulfonyl chloride (1t) with DOPO (2c).6d Encouraged by the findings described above, we then extended the modifed reaction condition to the coupling of aryl sulfonyl chlorides with dialkyl phosphonate, including diethyl phosphonate (2d), dimethyl phosphonate (2e), and diisopropyl phosphonate (2f). (S)-Aryl phosphonothioates can be efficiently synthesized under relatively mild conditions (80 °C, 12 h), and substituted aryl sulfonyl chlorides with electrondonating groups (Table 2, entries 3u−3w) or electronwithdrawing groups (Table 2, entries 3x−3aa) did not change the yields significantly, affording the corresponding products in 60−75% yields. Further investigations were also conducted to assess the potential for recycling of Pro/Cu catalyst in the model reaction. After completion of the reaction, the catalyst was easily recovered by centrifugalization, which was washed with ethyl ether, vacuumed and reused directly for the next run. The results indicated that the easy-to handle Pro/Cu catalyst was able to be reused in multiple consecutive catalytic runs (up to 10 runs) without loss of high reactivity (Scheme 2).

Scheme 3. Mechanistic Studies

readily carried out under a nitrogen atmosphere (85% yield, Scheme 3b), which indicated that the oxygen molecule was not the key factor in achieving the radical intermediate.4d Further studies were performed to shed light on the source of the radical. As shown in Scheme 3c, the reaction was almost completely quenched, and corresponding product 3a was not detected under the standard condition at room temperature. In contrast, 30% yield was afforded only in THF at 80 °C (Scheme 3d). These results illustrated that the reaction might proceed via a radical pathway and the temperature played a critical role in this Pro/Cu catalyzed coupling. Notably, the complex 4b, CuII(L-proline)2, can be successfully obtained in THF at 80 °C and conformed by HRMS (Scheme 3e). Furthermore, using 5 mol % 4b as the catalyst, this cross-coupling reaction can be readily performed in 80% yield (Scheme 3f), which showed that the catalyst CuII(Lproline)2 (4b) plays an important role in the formation of P− S−C bond. Additionally, the byproduct 4c in the reaction system was also examined by HRMS under the standard condition (Scheme 3g), further corroborated that the oxygen atom in sulfonyl chloride was reduced by excessive P(O)−H. On the basis of the above-mentioned experiments and the literature precedents,4d,6d,7 a plausible mechanism for the Pro/ Cu catalyzed P−S−C bond formation is shown in Scheme 4. Initially, CuCl2 and L-proline may form a complex 4b at 80 °C. Then, the active catalytic species, R-sulfonyl radical and chloro radical, were generated from R-sulfonyl chloride induced by the externally provided energy. Next, newly formed (CuII) intermediate A, which was achieved from ligand exchange reaction between 4b and P(O)−H, could act as an active catalyst undergoing the initial single electron transfer (SET) with the R-sulfonyl radical to generate (CuIII) intermediate B. At the same time, P-centered radical, phosphonic chloride

Scheme 2. Recycling Experiment of Pro/Cu

To further identify the role of L-proline in this transformation, some controlled experiments were performed. As illustrated in Scheme 3, desired product 3a was not observed under the standard condition when 4.0 equiv of radical trapping agent, 2,2,6,6-tetramethylpiperidinooxy (TEMPO), was involved. However, a tosyl radical, generated from tosyl chloride 1a, was successfully captured and byproduct 4a was obtained in 48% yield, thus suggesting the generation of a sulfonyl radical during the reaction (Scheme 3a). The model reaction was also 1534

DOI: 10.1021/acs.joc.7b02608 J. Org. Chem. 2018, 83, 1532−1537

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The Journal of Organic Chemistry

an oven at 60 °C for 2 h, the residue (catalyst) can be reused directly for the next run without further purification. O-Ethyl (S)-(p-Tolyl)phenylphosphonothioate (3a).6c Colorless oil, 130 mg, 89% (1.25 g, 86%, 5 mmol); 1H NMR (500 MHz, CDCl3): δ 7.68−7.64 (m, 2H), 7.50−7.47 (m, 1H), 7.38−7.34 (m, 2H), 7.17−7.15 (m, 2H), 7.02−7.00 (m, 2H), 4.38−4.29 (m, 2H), 2.28 (s, 3H), 1.39 (t, J = 7.1 Hz, 3H); 13C NMR (125 MHz, CDCl3): δ 139.1 (d, J = 3.0 Hz), 135.3 (d, J = 4.2 Hz), 132.3 (d, J = 3.2 Hz), 131.6 (d, J = 149.8 Hz), 131.3 (d, J = 10.5 Hz), 129.8 (d, J = 2.3 Hz), 128.0 (d, J = 14.8 Hz), 122.8 (d, J = 5.5 Hz), 62.3 (d, J = 6.9 Hz), 21.0, 16.2 (d, J = 6.7 Hz); 31P NMR (202 MHz, CDCl3): δ 41.8. (S)-(4-(tert-Butyl)phenyl) O-Ethyl Phenylphosphonothioate (3b).5 Colorless oil, 151 mg, 90%; 1H NMR (500 MHz, CDCl3): δ 7.66− 7.62 (m, 2H), 7.48−7.45 (m, 1H), 7.35−7.31 (m, 2H), 7.21 (s, 4H), 4.40−4.29 (m, 2H), 1.38 (t, J = 7.0 Hz, 3H), 1.25 (s, 9H); 13C NMR (125 MHz, CDCl3): δ 152.1 (d, J = 2.9 Hz), 134.9 (d, J = 4.1 Hz), 132.2 (d, J = 3.0 Hz), 131.4 (d, J = 148.9 Hz), 131.2 (d, J = 10.5 Hz), 127.9 (d, J = 15.1 Hz), 126.0 (d, J = 2.0 Hz), 122.7 (d, J = 5.9 Hz), 62.1 (d, J = 6.9 Hz), 34.3, 30.9, 16.1 (d, J = 6.8 Hz); 31P NMR (202 MHz, CDCl3): δ 40.4. O-Ethyl (S)-(4-Methoxyphenyl)phenylphosphonothioate (3c). Colorless oil, 132 mg, 86%; 1H NMR (500 MHz, CDCl3): δ 7.66− 7.62 (m, 2H), 7.50−7.47 (m, 1H), 7.38−7.34 (m, 2H), 7.18−7.16 (m, 2H), 6.74−6.72 (m, 2H), 4.39−4.27 (m, 2H), 3.74 (s, 3H), 1.39 (t, J = 7.0 Hz, 3H); 13C NMR (125 MHz, CDCl3): δ 160.3 (d, J = 2.5 Hz), 136.8 (d, J = 3.8 Hz), 132.2 (d, J = 2.9 Hz), 131.5 (d, J = 148.3 Hz) 131.3 (d, J = 10.5 Hz), 128.0 (d, J = 14.8 Hz), 116.6 (d, J = 5.0 Hz), 114.6 (d, J = 2.2 Hz), 62.2 (d, J = 7.0 Hz), 55.1, 16.2 (d, J = 6.7 Hz); 31 P NMR (202 MHz, CDCl3): δ 40.6; HRMS (ESI): m/z [M + H]+ calcd for C15H18O3PS+: 309.0709, found: 309.0708. (S)-(4-Chlorophenyl) O-Ethyl Phenylphosphonothioate (3d). Colorless oil, 133 mg, 85%; 1H NMR (500 MHz, CDCl3): δ 7.69− 7.64 (m, 2H), 7.53−7.49 (m, 1H), 7.41−7.37 (m, 2H), 7.24−7.21 (m, 2H), 7.19−7.17 (m, 2H), 4.40−4.27 (m, 2H), 1.40 (t, J = 7.0 Hz, 3H); 13 C NMR (125 MHz, CDCl3): δ 136.5 (d, J = 4.0 Hz), 135.4 (d, J = 3.2 Hz), 132.6 (d, J = 3.2 Hz), 131.3 (d, J = 10.6 Hz), 131.1 (d, J = 148.8 Hz), 129.2 (d, J = 2.1 Hz), 128.2 (d, J = 15.0 Hz), 125.0 (d, J = 5.3 Hz), 62.5 (d, J = 7.0 Hz), 16.2 (d, J = 6.8 Hz); 31P NMR (202 MHz, CDCl3): δ 40.3; HRMS (ESI): m/z [M + H]+ calcd for C14H15ClO2PS+: 313.0213, found: 313.0213. (S)-(4-Bromophenyl) O-Ethyl Phenylphosphonothioate (3e). Colorless oil, 139 mg, 78%; 1H NMR (500 MHz, CDCl3): δ 7.69− 7.64 (m, 2H), 7.52−7.48 (m, 1H), 7.40−7.36 (m, 2H), 7.34−7.31 (m, 2H), 7.17−7.15 (m, 2H), 4.37−4.28 (m, 2H), 1.39 (t, J = 7.0 Hz, 3H); 13 C NMR (125 MHz, CDCl3): δ 136.6 (d, J = 4.2 Hz), 132.5 (d, J = 3.2 Hz), 132.0 (d, J = 2.2 Hz), 131.2 (d, J = 10.6 Hz), 131.0 (d, J = 149.5 Hz), 128.1 (d, J = 15.0 Hz), 125.6 (d, J = 5.4 Hz), 123.5 (d, J = 3.5 Hz), 62.5 (d, J = 7.1 Hz), 16.1 (d, J = 6.6 Hz); 31P NMR (202 MHz, CDCl3): δ 39.5; HRMS (ESI): m/z [M + H]+ calcd for C14H15BrO2PS+: 356.9708, found: 356.9706. O-Ethyl (S)-(4-(Trifluoromethyl)phenyl)phenylphosphonothioate (3f). Colorless oil, 128 mg, 74%; 1H NMR (500 MHz, CDCl3): δ 7.71−7.67 (m, 2H), 7.54−7.51 (m, 1H), 7.47 (s, 4H), 7.42−7.38 (m, 2H), 4.42−4.30 (m, 2H), 1.42 (t, J = 7.0 Hz, 3H); 13C NMR (125 MHz, CDCl3): δ 135.3 (d, J = 4.3 Hz), 132.8 (d, J = 2.9 Hz), 131.3 (d, J = 10.8 Hz), 131.2 (d, J = 149.3 Hz), 131.0 (d, J = 2.3 Hz), 130.8 (d, J = 2.6 Hz), 128.3 (d, J = 15.0 Hz), 123.7 (q, J = 270.3 Hz), 125.8 (d, J = 3.3 Hz), 62.9 (d, J = 7.1 Hz), 16.3 (d, J = 6.6 Hz); 31P NMR (202 MHz, CDCl3): δ 42.1; HRMS (ESI): m/z [M + H]+ calcd for C15H15F3O2PS+: 347.0477, found: 347.0475. O-Ethyl (S)-Mesitylphenylphosphonothioate (3g). Colorless oil, 131 mg, 82%; 1H NMR (500 MHz, CDCl3): δ 7.67−7.63 (m, 2H), 7.49−7.46 (m, 1H), 7.37−7.33 (m, 2H), 6.84 (s, 2H), 4.27−4.20 (m, 2H), 2.25 (s, 6H), 2.21 (s, 3H), 1.35 (t, J = 7.0 Hz, 3H); 13C NMR (125 MHz, CDCl3): δ 143.9 (d, J = 3.9 Hz), 138.9 (d, J = 2.8 Hz), 132.6 (d, J = 144.7 Hz), 132.1, 130.9 (d, J = 10.6 Hz), 129.1 (d, J = 2.4 Hz), 128.0 (d, J = 14.5 Hz), 121.2 (d, J = 6.5 Hz), 62.3 (d, J = 7.2 Hz), 22.0, 20.7, 16.2 (d, J = 6.6 Hz); 31P NMR (202 MHz, CDCl3): δ 38.9; HRMS (ESI): m/z [M + H]+ calcd for C17H22O2PS+: 321.1073, found: 321.1071.

Scheme 4. Proposed Mechanism

radical C was generated via a radical transfer process between P(O)−H and the chloro radical. Finally, in situ formed intermediate B was attacked by phosphonic chloride radical C, undergoes reductive elimination of an oxygen atom to afford the target product, along with the regeneration of the chloro radical and LCuI species E. Subsequently, the latter rapidly acted with chloro radical and L-proline, affording complex 4b to fulfill the catalytic cycle. In summary, we have described a copper catalyzed coupling of P(O)−H with sulfuryl chlorides under relatively mild conditions. Using natural product L-proline as the ligand greatly broadened the substrate scope and provided (S)-aryl/alkyl phosphinothioates or phosphorothioates in good to excellent yields. In addition, the easy-to handle and recyclable Pro/Cu catalyst make this reaction practical and highly attractive. Further detailed mechanistic studies and applications based on this efficient transformation are underway in our laboratory.

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EXPERIMENTAL SECTION

General Methods. All chemicals were obtained from commercial suppliers and used directly without further purification. 1H NMR (500 MHz) and 13C NMR (125 MHz) spectras were recorded on Bruker AVANCE III (500 MHz) spectrometer with CDCl3, DMSO-d6, or MeOD as solvents. The chemical shifts δ are reported in ppm relative to tetra-methylsilane. Reference peaks for chloroform in 1H NMR and 13 C NMR spectra were set at 7.26 and 77.0 ppm. For DMSO-d6, the reference peaks were set as follows: 1H NMR: TMS at 0.00 ppm, DMSO at 2.50 ppm; 13C NMR: DMSO at 40.0 ppm, and for MeOD, these were set as follows: 1H NMR: TMS at 0.00 ppm, MeOD at 3.3 ppm; 13C NMR: MeOD at 48.8 ppm. High-resolution mass spectras (HRMS) were obtained on Ultrahigh Resolution Hybrid Qh-Fourier Transform Mass Spectrometer, SolariX70 FT-ICR MS (Bruker, Switzerland) with ESI. Melting points were determined on a WRS1B melting point apparatus and were uncorrected. General Experimental Procedure. Compound 1, aryl/alkyl sulfonyl chlorides (0.5 mmol), compound 2, P(O)−H (2.0 mmol), CuCl2·2H2O (0.025 mmol), and L-proline (0.05 mmol) were added to a glass tube, and then 1.0 mL of THF was added. The reaction mixture was stirred at 80 °C for 3−12 h. After completion of the reaction, the mixture was concentrated under reduced pressure and extracted with Et2O (10.0 mL × 3). Then, the organic phases were combined and dried with anhydrous MgSO4, purified by silica gel column chromatography (petroleum ether/ethyl acetate as the eluent) to afford corresponding product 3. After washed with Et2O and dried in 1535

DOI: 10.1021/acs.joc.7b02608 J. Org. Chem. 2018, 83, 1532−1537

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The Journal of Organic Chemistry

(S)-(4-Chlorophenyl) O-Isopropyl Phenylphosphonothioate (3o). Colorless oil, 135 mg, 83%; 1H NMR (500 MHz, CDCl3): δ 7.70− 7.66 (m, 2H), 7.51−7.48 (m, 1H), 7.41−7.37 (m, 2H), 7.26−7.24 (m, 2H), 7.18−7.17 (m, 2H), 5.01−4.95 (m, 1H), 1.42−1.36 (m, 6H); 13C NMR (125 MHz, CDCl3): δ 136.4 (d, J = 4.1 Hz), 135.3 (d, J = 3.2 Hz), 132.4 (d, J = 2.7 Hz), 131.9 (d, J = 145.9 Hz), 131.3 (d, J = 10.6 Hz), 129.1 (d, J = 1.7 Hz), 128.2 (d, J = 15.0 Hz), 125.3 (d, J = 4.6 Hz), 72.4 (d, J = 7.2 Hz), 24.1 (d, J = 3.6 Hz), 24.0 (d, J = 5.1 Hz); 31P NMR (202 MHz, CDCl3): δ 38.4; HRMS (ESI): m/z [M + H]+ calcd for C15H17ClO2PS+: 327.0370, found: 327.0371. (S)-(4-Bromophenyl) O-Isopropyl Phenylphosphonothioate (3p). Colorless oil, 144 mg, 78%; 1H NMR (500 MHz, CDCl3): δ 7.70− 7.66 (m, 2H), 7.50−7.47 (m, 1H), 7.40−7.37 (m, 2H), 7.33−7.31 (m, 2H), 7.19−7.17 (m, 2H), 5.01−4.94 (m, 1H), 1.41−1.36 (m, 6H); 13C NMR (125 MHz, CDCl3): δ 136.7 (d, J = 4.2 Hz), 132.5 (d, J = 3.1 Hz), 132.1 (d, J = 2.0 Hz), 132.0 (d, J = 147.4 Hz), 131.4 (d, J = 10.7 Hz), 128.2 (d, J = 15.0 Hz), 126.0 (d, J = 5.3 Hz), 123.6 (d, J = 3.3 Hz), 72.5 (d, J = 7.2 Hz), 24.2 (d, J = 3.7 Hz), 24.0 (d, J = 5.1 Hz); 31P NMR (202 MHz, CDCl3): δ 38.5; HRMS (ESI): m/z [M + H]+ calcd for C15H17BrO2PS+: 370.9865, found: 370.9861. (S)-Butyl O-Isopropyl Phenylphosphonothioate (3q). Colorless oil, 105 mg, 77%; 1H NMR (500 MHz, CDCl3): δ 7.89−7.85 (m, 2H), 7.55−7.52 (m, 1H), 7.49−7.45 (m, 2H), 4.95−4.88 (m, 1H), 2.75− 2.70 (m, 2H), 1.57−1.51 (m, 2H), 1.42−1.40 (m, 3H), 1.38−1.36 (m, 3H), 1.34−1.28 (m, 2H), 0.83 (t, J = 7.5 Hz, 3H); 13C NMR (125 MHz, CDCl3): δ 133.4 (d, J = 149.6 Hz), 132.1 (d, J = 2.7 Hz), 131.0 (d, J = 10.8 Hz), 128.3 (d, J = 14.7 Hz), 71.3 (d, J = 6.9 Hz), 32.5 (d, J = 5.4 Hz), 30.0 (d, J = 2.5 Hz), 24.2 (d, J = 3.6 Hz), 24.0 (d, J = 5.0 Hz), 21.5, 13.3; 31P NMR (202 MHz, CDCl3): δ 42.2; HRMS (ESI): m/z [M + H]+ calcd for C13H22O2PS+: 273.1073, found: 273.1072. (S)-6-(Mesitylthio)dibenzo[c,e][1,2]oxaphosphinine 6-Oxide (3r). White solid,163 mg, 89%, mp 149.2−150.1 °C; 1H NMR (500 MHz, CDCl3): δ 7.84−7.80 (m, 2H), 7.73−7.71 (m, 1H), 7.67−7.64 (m, 1H), 7.46−7.42 (m, 1H), 7.30−7.26 (m, 1H), 7.16−7.11 (m, 2H), 6.64 (s, 2H), 2.14 (s, 6H), 2.11 (s, 3H); 13C NMR (125 MHz, CDCl3): δ 150.2 (d, J = 9.7 Hz), 144.0 (d, J = 4.1 Hz), 139.5 (d, J = 3.5 Hz), 135.9 (d, J = 7.6 Hz), 133.5, 130.5 (d, J = 10.1 Hz), 130.2, 129.1 (d, J = 3.0 Hz), 128.4 (d, J = 14.5 Hz), 125.7 (d, J = 129.8 Hz), 124.5, 124.1, 123.2 (d, J = 11.1 Hz), 121.5 (d, J = 11.2 Hz), 119.6 (d, J = 6.9 Hz), 119.2 (d, J = 9.2 Hz), 21.9, 20.8; 31P NMR (202 MHz, CDCl3): δ 32.8; HRMS (ESI): m/z [M + H]+ calcd for C21H20O2PS+: 367.0916, found: 367.0912. (S)-6-(Naphthalen-2-ylthio)dibenzo[c,e][1,2]oxaphosphinine 6Oxide (3s).6d White solid, 153 mg, 82%, 168.3−169.6 °C; 1H NMR (500 MHz, DMSO-d6): δ 8.07−8.05 (m, 1H), 7.94−7.90 (m, 1H), 7.85−7.80 (m, 4H), 7.72−7.70 (m, 2H), 7.64 (s, 1H), 7.55−7.51 (m, 2H), 7.43−7.40 (m, 1H), 7.34−7.33 (m, 1H), 7.25−7.24 (m, 1H), 7.15−7.12 (m, 1H); 13C NMR (125 MHz, CDCl3): δ 150.4 (d, J = 9.7 Hz), 136.3 (d, J = 5.4 Hz), 136.3 (d, J = 7.3 Hz), 133.7 (d, J = 2.6 Hz), 133.1 (d, J = 2.9 Hz), 132.9 (d, J = 2.2 Hz), 131.7 (d, J = 3.2 Hz), 130.6 (d, J = 10.3 Hz), 130.3, 128.5 (d, J = 2.1 Hz), 128.4 (d, J = 14.8 Hz), 127.6, 127.3, 127.1, 126.4, 124.6 (d, J = 133.1 Hz), 124.6, 124.3, 123.1 (d, J = 11.4 Hz), 121.5 (d, J = 11.6 Hz), 121.1 (d, J = 6.3 Hz), 119.7 (d, J = 7.1 Hz); 31P NMR (202 MHz, CDCl3) δ 32.6. (S)-6-(Butylthio)dibenzo[c,e][1,2]oxaphosphinine 6-Oxide (3t).6d Colorless oil, 123 mg, 81%; 1H NMR (500 MHz, CDCl3): δ 7.91− 7.86 (m, 1H), 7.82−7.77 (m, 2H), 7.58−7.55 (m, 1H), 7.41−7.38 (m, 1H), 7.28−7.24 (m, 1H), 7.16−7.10 (m, 2H), 2.84−2.68 (m, 2H), 1.55−1.48 (m, 2H), 1.26−1.19 (m, 2H), 0.74 (t, J = 7.5 Hz, 3H); 13C NMR (125 MHz, CDCl3): δ 149.3 (d, J = 9.5 Hz), 135.7 (d, J = 7.5 Hz), 133.5 (d, J = 2.8 Hz), 130.4, 130.1 (d, J = 10.7 Hz), 128.3 (d, J = 14.8 Hz), 125.7 (d, J = 135.8 Hz), 124.9, 124.7, 123.6 (d, J = 11.0 Hz), 122.0 (d, J = 11.8 Hz), 120.1 (d, J = 6.6 Hz), 32.6 (d, J = 4.8 Hz), 29.6 (d, J = 3.5 Hz), 21.3, 13.1; 31P NMR (202 MHz, CDCl3): δ 37.6. O,O-Diethyl (S)-(p-Tolyl)phosphorothioate (3u).4d Colorless oil, 98 mg, 75%; 1H NMR (500 MHz, CDCl3): δ7.44 (d, J = 7.0 Hz,2H), 7.15 (d, J = 8.0 Hz, 2H), 4.25−4.12 (m, 4H), 2.34 (s, 3H), 1.31 (t, J = 7.0 Hz, 3H); 13C NMR (125 MHz, CDCl3): δ 139.1 (d, J = 1.9 Hz), 134.4 (d, J = 5.0 Hz), 130 (d, J = 2.3 Hz), 122.6 (d, J = 7.5 Hz), 63.8

O-Ethyl (S)-(Naphthalen-2-yl)phenylphosphonothioate (3h). Colorless oil, 144 mg, 88%; 1H NMR (500 MHz, CDCl3): δ 7.77−7.76 (m, 1H), 7.73−7.72 (m, 1H), 7.67−7.61 (m, 4H), 7.45−7.39 (m, 3H), 7.33−7.27 (m, 3H), 4.40−4.32 (m, 2H), 1.37 (t, J = 7.0 Hz, 3H); 13C NMR (125 MHz, CDCl3): δ 135.3 (d, J = 5.3 Hz), 133.2 (d, J = 2.4 Hz), 132.7 (d, J = 1.9 Hz), 132.3 (d, J = 3.0 Hz), 131.4 (d, J = 3.2 Hz), 131.2 (d, J = 148.4 Hz), 131.2 (d, J = 10.7 Hz), 130.5 (d, J = 11.3 Hz), 128.5, 128.2 (d, J = 13.3 Hz), 128.0 (d, J = 14.9 Hz), 127.4 (d, J = 3.3 Hz), 126.8, 126.3, 62.3 (d, J = 6.9 Hz), 16.1 (d, J = 6.8 Hz); 31P NMR (202 MHz, CDCl3): δ 41.7; HRMS (ESI): m/z [M + H]+ calcd for C18H17O2PS+: 329.0760, found: 329.0758. O-Ethyl (S)-(Thiophen-2-yl)phenylphosphonothioate (3i). Colorless oil, 109 mg, 77%; 1H NMR (500 MHz, CDCl3): δ 7.67−7.63 (m, 2H), 7.52−7.49 (m, 1H), 7.38−7.37 (m, 2H), 7.32−7.31 (m, 1H), 6.86 (s, 2H), 4.44−4.35 (m, 2H), 1.43 (t, J = 7.0 Hz, 3H); 13C NMR (125 MHz, CDCl3): δ 136.3 (d, J = 5.4 Hz), 132.5 (d, J = 2.8 Hz), 131.3 (d, J = 10.5 Hz), 131.0 (d, J = 3.6 Hz), 130.2 (d, J = 151.7 Hz), 128.0 (d, J = 15.0 Hz), 127.5 (d, J = 3.3 Hz), 123.3 (d, J = 7.3 Hz), 62.4 (d, J = 6.9 Hz), 16.1 (d, J = 6.8 Hz); 31P NMR (202 MHz, CDCl3): δ 39.5; HRMS (ESI): m/z [M + H]+ calcd for C12H14O2PS2+: 285.0167, found: 285.0166. (S)-Butyl O-Ethyl Phenylphosphonothioate (3j). Colorless oil, 83 mg, 64%; 1H NMR (500 MHz, CDCl3): δ 7.90−7.86 (m, 2H), 7.56− 7.53 (m, 1H), 7.50−7.46 (m, 2H), 4.29−4.22 (m, 2H), 2.76−2.70 (m, 2H), 1.58−1.52 (m, 2H), 1.39 (t, J = 7.0 Hz, 3H), 1.35−1.31 (m, 2H), 0.83 (t, J = 7.0 Hz, 3H); 13C NMR (125 MHz, CDCl3): δ 132.6 (d, J = 148 Hz), 132.2 (d, J = 3.2 Hz), 130.9 (d, J = 10.7 Hz), 128.3 (d, J = 14.5 Hz), 61.8 (d, J = 6.8 Hz), 32.4 (d, J = 5.1 Hz), 29.9 (d, J = 2.8 Hz), 21.4, 16.2 (d, J = 6.8 Hz), 13.2; 31P NMR (202 MHz, CDCl3): δ 43.4; HRMS (ESI): m/z [M + H]+ calcd for C12H20O2PS+: 259.0916, found: 259.0915. (S)-(2-Chloroethyl) O-Ethyl Phenylphosphonothioate (3k). Colorless oil, 110 mg, 83%; 1H NMR (500 MHz, CDCl3): δ 7.89−7.85 (m, 2H), 7.60−7.56 (m, 1H), 7.52−7.48 (m, 2H), 4.30−4.24 (m, 2H), 3.64−3.57 (m, 2H), 3.13−3.04 (m, 2H), 1.40 (t, J = 7.5 Hz, 3H); 13C NMR (125 MHz, CDCl3): δ 132.8 (d, J = 3.3 Hz), 132.3 (d, J = 149.5 Hz), 131.1 (d, J = 10.9 Hz), 128.6 (d, J = 15.0 Hz), 62.6 (d, J = 6.9 Hz), 43.3 (d, J = 3.1 Hz), 31.9 (d, J = 2.6 Hz), 16.3 (d, J = 6.8 Hz); 31P NMR (202 MHz, CDCl3): δ 42.1; HRMS (ESI): m/z [M + H]+ calcd for C10H15ClO2PS+: 265.0213, found: 265.0211. (S)-Cyclopropyl O-Ethyl Phenylphosphonothioate (3l). Colorless oil, 63 mg, 52%; 1H NMR (500 MHz, CDCl3): δ 7.84−7.80 (m, 2H), 7.50−7.47 (m, 1H), 7.42−7.38 (m, 2H), 4.27−74.15 (m, 2H), 1.76− 1.71 (m, 1H), 1.34 (t, J = 7.1 Hz, 3H), 0.72−0.70 (m, 2H), 0.43−0.40 (m, 1H), 0.39−0.36 (m, 1H); 13C NMR (125 MHz, CDCl3): δ 132.7 (d, J = 146.4 Hz), 132.4 (d, J = 3.1 Hz), 131.3 (d, J = 10.9 Hz), 128.3 (d, J = 14.7 Hz), 62.0 (d, J = 6.8 Hz), 16.3 (d, J = 6.7 Hz), 9.9 (d, J = 2.6 Hz), 7.9 (d, J = 5.8 Hz), 7.8 (d, J = 6.6 Hz); 31P NMR (202 MHz, CDCl3): δ 42.8; HRMS (ESI): m/z [M + Na]+ calcd for C11H15O2PSNa+: 265.0423, found: 265.0423. O-Isopropyl (S)-(p-Tolyl)phenylphosphonothioate (3m). Colorless oil, 138 mg, 90%; 1H NMR (500 MHz, CDCl3): δ 7.70−7.66 (m, 2H), 7.50−7.47 (m, 1H), 7.39−7.35 (m, 2H), 7.19−7.18 (m, 2H), 7.01− 7.00 (m, 2H), 5.03-.94 (m, 1H), 2.28 (s, 3H), 1.41−1.36 (m, 6H); 13C NMR (125 MHz, CDCl3): δ 138.9 (d, J = 2.9 Hz), 135.3 (d, J = 4.1 Hz), 132.4 (d, J = 148.4 Hz), 132.2 (d, J = 2.9 Hz), 131.4 (d, J = 10.5 Hz), 129.7 (d, J = 2.0 Hz), 128.0 (d, J = 14.9 Hz), 123.0 (d, J = 6.0 Hz), 72.0 (d, J = 7.3 Hz), 24.2(d, J = 3.4 Hz), 24.0 (d, J = 5.2 Hz), 21.1; 31P NMR (202 MHz, CDCl3): δ 38.8; HRMS (ESI): m/z [M + H]+ calcd for C16H20O2PS+: 307.0916, found: 307.0915. (S)-(4-(tert-Butyl)phenyl) O-Isopropyl Phenylphosphonothioate (3n). Colorless oil, 160 mg, 92%; 1H NMR (500 MHz, CDCl3): δ 7.69−7.65 (m, 2H), 7.48−7.46 (m, 1H), 7.37−7.33 (m, 2H), 7.25− 7.20 (m, 4H), 5.02−4.95 (m, 1H), 1.40−1.37 (m, 6H), 1.26 (s, 9H); 13 C NMR (125 MHz, CDCl3): δ 152.1 (d, J = 3.0 Hz), 135.0 (d, J = 4.1 Hz), 132.4 (d, J = 149.0 Hz), 132.1 (d, J = 2.9 Hz), 131.3 (d, J = 10.6 Hz), 128.0 (d, J = 14.9 Hz), 126.0, 123.0 (d, J = 5.4 Hz), 72.0 (d, J = 7.2 Hz), 34.5, 31.1, 24.2 (d, J = 3.5 Hz), 24.0 (d, J = 5.2 Hz); 31P NMR (202 MHz, CDCl3): δ 39.1; HRMS (ESI): m/z [M + H]+ calcd for C19H26O2PS+: 349.1386, found: 349.1385. 1536

DOI: 10.1021/acs.joc.7b02608 J. Org. Chem. 2018, 83, 1532−1537

Note

The Journal of Organic Chemistry (d, J = 6.1 Hz), 21.0, 15.9 (d, J = 7.3 Hz); 31P NMR (202 MHz, CDCl3): δ 23.3. O,O-Diethyl (S)-(4-Methoxyphenyl) Phosphorothioate (3v).4e Colorless oil, 94 mg, 68%; 1H NMR (500 MHz, CDCl3): δ 7.48− 7.46 (m, 2H), 6.88 (d, J = 9.0 Hz, 2H), 4.24−4.12 (m, 4H), 3.80 (s, 3H), 1.31 (t, J = 7.0 Hz, 6H); 13C NMR (125 MHz, CDCl3): δ 160.3 (d, J = 3.0 Hz), 136.2 (d, J = 5.0 Hz), 116.4 (d, J = 7.4 Hz), 114.8 (d, J = 2.6 Hz), 63.8 (d, J = 6.3 Hz), 55.2, 15.9 (d, J = 7.1 Hz); 31P NMR (202 MHz, CDCl3): δ 23.5. O,O-Diethyl (S)-Mesityl Phosphorothioate (3w). Colorless oil, 92 mg, 64%; 1H NMR (500 MHz, CDCl3): δ 6.94 (s, 2H), 4.17−4.05 (m, 4H), 2.53 (s, 6H), 2.25 (d, J = 2.0 Hz, 3H), 1.28 (t, J = 7.0 Hz, 6H); 13 C NMR (125 MHz, CDCl3): δ 143.7 (d, J = 4.8 Hz), 139.2 (d, J = 3.9 Hz), 129.2 (d, J = 3.6 Hz), 121.0 (d, J = 7.9 Hz), 63.9 (d, J = 7.3 Hz), 22.2, 20.8, 15.9 (d, J = 6.8 Hz); 31P NMR (202 MHz, CDCl3): δ 23.5; HRMS (ESI): m/z [M + H]+ calcd for C13H22O3PS+: 289.1022, found: 289.1020. O,O-Diethyl (S)-(3-Nitrophenyl) Phosphorothioate (3x).4e Colorless oil, 100 mg, 69%; 1H NMR (500 MHz, CDCl3): δ 8.45−8.44 (m, 1H), 8.23 (d, J = 8.0 Hz, 1H), 7.94 (d, J = 8.0 Hz, 1H), 7.57 (t, J = 8.0 Hz, 1H), 4.31−4.19 (m, 4H), 1.36 (t, J = 7.0 Hz, 6H); 13C NMR (125 MHz, CDCl3): δ 148.3, 140.11 (d, J = 5.1 Hz), 130.0, 129.5 (d, J = 7.3 Hz), 128.9 (d, J = 5.5 Hz), 123.7, 64.5 (d, J = 6.5 Hz), 15.9 (d, J = 7.2 Hz); 31P NMR (202 MHz, CDCl3): δ 20.8. (S)-(4-Chlorophenyl) O,O-Diethyl Phosphorothioate (3y).4e Colorless oil, 99 mg, 71%; 1H NMR (500 MHz, CDCl3): δ7.52−7.49 (m, 2H), 7.33−7.32 (m, 2H), 4.26−4.14 (m, 4H), 1.32 (t, J = 7.0 Hz, 6H); 13 C NMR (125 MHz, CDCl3): δ 135.6 (d, J = 5.1 Hz), 135.3 (d, J = 3.5 Hz), 129.4 (d, J = 2.3 Hz), 124.9 (d, J = 7.1 Hz), 64.1 (d, J = 6.3 Hz), 15.9 (d, J = 7.1 Hz); 31P NMR (202 MHz, CDCl3): δ 22.1. (S)-(4-Chlorophenyl) O,O-Dimethyl Phosphorothioate (3z).4d Colorless oil, 76 mg, 60%; 1H NMR (500 MHz, CDCl3): δ 7.50 (d, J = 7.0 Hz, 2H), 7.33 (d, J = 8.5 Hz, 2H), 3.84 (s, 3H), 3.81 (s, 3H); 13 C NMR (125 MHz, CDCl3): δ 135.7 (d, J = 5.1 Hz), 135.6 (d, J = 3.6 Hz), 129.6 (d, J = 2.4 Hz), 124.4 (d, J = 7.4 Hz), 54.3 (d, J = 6.2 Hz); 31P NMR (202 MHz, CDCl3): δ 24.0. (S)-(4-Chlorophenyl) O,O-Diisopropyl Phosphorothioate (3aa). Colorless oil, 114 mg, 74%; 1H NMR (500 MHz, CDCl3): δ 7.54− 7.52 (m, 2H), 7.31 (d, J = 8.5 Hz, 2H), 4.80−4.73 (m, 2H), 1.33 (d, J = 6.5 Hz, 6H), 1.27 (d, J = 6.5 Hz, 6H); 13C NMR (125 MHz, CDCl3): δ 135.3 (d, J = 5.4 Hz), 134.9 (d, J = 3.3 Hz), 129.2 (d, J = 2.2 Hz), 125.7 (d, J = 7.1 Hz), 73.4 (d, J = 6.8 Hz), 23.7 (d, J = 4.3 Hz), 23.4 (d, J = 5.6 Hz); 31P NMR (202 MHz, CDCl3): δ 18.5; HRMS (ESI): m/z [M + H]+ calcd for C12H19ClO3PS+: 309.0476, found: 309.0474. 2,2,6,6-Tetramethylpiperidin-1-yl-4-methylbenzenesulfonate (4a). White solid, 75 mg, 48%; 1H NMR (500 MHz, MeOD): δ 7.70 (s, 2H), 7.23 (s, 2H), 2.37 (s, 3H), 1.75−1.63 (m, 6H), 1.40 (s, 12H), 13 C NMR (125 MHz, MeOD): δ 143.4 (d, J = 6.1 Hz), 141.5 (d, J = 2.8 Hz), 129.6, 126.7, 57.6, 35.6, 27.4, 21.1, 16.9.

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Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was supported by the NSF of China (21302127 and 21502116) and the collaborative innovation funding of Shanghai Institute of Technology (XTCX2016-7).

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REFERENCES

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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.joc.7b02608. 1

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H NMR, 13C NMR and 31P NMR spectra for all products (PDF) Crystallographic data for the compound 3s (CIF)

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Corresponding Authors

*E-mail: [email protected]. *E-mail: [email protected] ORCID

Xinghua Zhang: 0000-0002-0151-6709 1537

DOI: 10.1021/acs.joc.7b02608 J. Org. Chem. 2018, 83, 1532−1537