Synlett, Table of Contents Synlett 2021; 32(06): 593-600DOI: 10.1055/a-1335-7902 letter Electrocatalytic Synthesis of gem-Bisarylthio Enamines and α-Phenylthio Ketones via a Radical Process under Mild Conditions Authors Yong-Zhou Pan Shi-Yan Cheng Qian-Yu Li Hai-Tao Tang Ying-Ming Pan Xiu-Jin Meng∗ Zu-Yu Mo∗ Recommend Article Abstract Buy Article(opens in new window) All articles of this category(opens in new window) Abstract The novel method for the synthesis of gem-bisarylthio enamines and α-phenylthio ketones was developed via the coupling of α-substituted vinyl azides with thiols in the presence of tetrabutylammonium iodide (TBAI) as a redox catalyst and electrolyte at room temperature. Electronic properties were crucial in the generated products. This protocol features metal- and oxidant-free materials, broad tolerance of substrates, and mild reaction conditions. Key words Key wordselectrocatalytic - vinyl azides - thiophenols - gem-bisarylthio enamines - metal-free Full Text References References and Notes 1a Zhang X, Liu C, Deng Y, Cao S. Org. Biomol. Chem. 2020; 18: 7540 1b Fujita T, Fuchibe K, Ichikawa J. Angew. Chem. Int. Ed. 2019; 58: 390 1c Zhang X, Cao S. Tetrahedron Lett. 2017; 58: 375 1d Chelucci G. Chem. Rev. 2012; 112: 1344 1e Hu J, Han X, Yuan Y, Shi Z. Angew. Chem. Int. Ed. 2017; 56: 13342 1f Hu J, Zhao Y, Shi Z. Nat. Catal. 2018; 1: 860 1g Yoo W.-J, Kondo J, Rodríguez-Santamaría JA, Nguyen TV. Q, Kobayashi S. Angew. Chem. Int. Ed. 2019; 58: 6772 1h Guo Y.-Q, Wang R, Song H, Liu Y, Wang Q. Org. Lett. 2020; 22: 709 2 Yao C, Wang S, Norton J, Hammond M. J. Am. Chem. Soc. 2020; 142: 4793 3 Uetake Y, Isoda M, Niwa T, Hosoya T. Org. Lett. 2019; 21: 4933 4 Gao Y, Wu Z.-Q, Engle KM. Org. Lett. 2020; 22: 5235 5 Davis FA, Mancinelli PA. J. Org. Chem. 1980; 45: 2597 6 Ni J, Mao X, Zhang A. Adv. Synth. 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Lett. 2017; 19: 6240 23a Hassner A, Belinka BA. Jr. J. Am. Chem. Soc. 1980; 102: 6185 23b Kong X, Liu Y, Lin L, Chen Q, Xu B. Green Chem. 2019; 21: 3796 24 General Procedure for the Synthesis of gem-Bisphenylthio Enamine 3aa The azide 1a (0.3 mmol), thiophenol 2a (0.75 mmol), DBU (0.6 mmol), and TBAI (0.03 mmol) were placed in a 10 mL three-necked round-bottomed flask. The flask was equipped with a condenser and graphite rod as cathode and anode. MeOH (6.0 mL) was added. The electrolysis was carried out under air atmosphere at room temperature using a constant current of 3 mA until complete consumption of the substrate (monitored by TLC, about 1 h). The reaction mixture was concentrated, and the residue was chromatographed through silica gel eluting with ethyl acetate/petroleum ether to give the product 3aa. 25 Analytical Data for Compound 3aa 88% yield; yellow solid; mp 94.1–95.4 °C. Analytical TLC on silica gel. Rf = 0.48 (hexane/ether; 6.1). 1H NMR (400 MHz, CDCl3): δ = 8.19 (d, J = 8.4 Hz, 2 H), 7.66 (d, J = 8.4 Hz, 2 H), 7.22–7.17 (m, 2 H), 7.14–7.04 (m, 6 H), 5.04 (s, 2 H), 2.33 (s, 3 H), 2.31 (s, 3 H). 13C NMR (100 MHz, CDCl3): δ = 158.0, 148.1, 143.8, 136.0, 135.3, 134.7, 131.8, 129.9, 129.7, 129.1, 127.8, 126.5, 123.5, 91.0, 21.0, 21.0. HRMS (ESI): m/z calcd for C22H21N2O2S2 [M + H]+: 409.1039; found: 409.1036. Supplementary Material Supplementary Material Supporting Information (PDF) (opens in new window)
