Radical reaction of S-phenyl chlorothioformate with alkyl iodides: free radical-mediated carboxylation approach

Abstract

Free radical-mediated carboxylation is achieved by treatment of alkyl iodides with S-phenyl chlorothioformate and bis(tributyltin) with irradiation at 300 nm.

References

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11. A typical procedure for the radical reaction of S-phenyl chlorothioformate with an alkyl iodide is as follows. A benzene solution (0.5 ml, 0.4 M in the iodide) of cyclohexyl iodide (42 mg, 0.2 mmol), S-phenyl chlorothioformate (70 mg, 0.4 mmol) and bis(tributyltin)(140 mg, 0.24 mmol) in a quartz tube was degassed for 10 min and then irradiated at 300 nm in a photochemical reactor for 9 h. The reaction mixture was concentrated under reduced pressure. EtOAc (3 ml), water (2–3 drops) and KF (116 mg, 2 mmol) were then added and the mixture was stirred at room temperature for 30 min. After the mixture was filtered through a short column of silica gel, the filtrate was concentrated under reduced pressure. The crude product was purified by flash silica gel column chromatography to give S-phenyl cyclohexanecarbothioate (25 mg, 56%) as a colorless oil: δ_H(200 MHz, CDCl₃) 1.23–1.54 (m, 4 H), 1.56–1.87 (m, 4 H), 1.88–2.13 (m, 2 H), 2.53–2.68 (m, 1 H), 7.38 (s, 5 H); δ_C(50 MHz, CDCl₃) 25.4, 25.5, 29.5, 52.4, 127.8, 129.1, 129.2, 134.4, 200.6; ν_max(NaCl)/cm^–1 2928, 1708, 1066, 950.