Synthesis of Thioethers by InI3-Catalyzed Substitution of Siloxy Group Using Thiosilanes

Abstract

Abstract:The substitution of a siloxy group using thiosilanes smoothly occurred in the presence of InI 3 catalyst to yield the corresponding thioethers. InI 3 was a specifically effective catalyst in this reaction system, while other typical Lewis acids such as BF 3 ·OEt 2 , AlCl 3 , and TiCl 4 were ineffective. Various silyl ethers such as primary alkyl, secondary alkyl, tertiary alkyl, allylic, benzylic, and propargylic types were applicable. In addition, bulky OSitBuMe 2 and OSiiPr 3 groups, other than the OSiMe 3 group, were successfully substituted. The substitution reaction of enantiopure secondary benzylic silyl ether yielded the corresponding racemic thioether product, which suggested that the reaction of tertiary alkyl, secondary alkyl, benzylic, and propargylic silyl ethers would proceed via a S N 1 mechanism.

Production of Alkyl Aryl Sulfides from Aromatic Disulfides and Alkyl Carboxylates via a Disilathiane–Disulfide Interchange Reaction

“…The chemicals 1,1,1,3,3,3-Hexamethyldisilathiane, K 2 CO 3 , disulfides 1, diphenyl diselenide (4), and alkyl carboxylates 2 were purchased from common commercial suppliers, and were used as received. The 4-[(Trimethylsilyl)thio] toluene (6) was synthesized according to a procedure described in the literature. [5b] All reactions were performed under air, unless otherwise noted.…”

“…Thiosilanes occupy a promising class of organosulfur nucleophiles, due to their high reactivity that derives from relatively weak SiÀ S bonds and to the oxophilicity of their silicon atoms. [4] These characteristics make thiosilanes particularlly desirable for use in deoxygenative condensation with alkyl carboxylates [5] and silyl ethers, [6] as well as in the replacement of alkyl halides in the context of Williamson-type sulfide synthesis. [7] A significant achievement for sulfide formation involves the indium-catalyzed substitution of alkyl acetates by prepared thiosilanes.…”