Umpolung Synthesis of Selenoesters and Telluroesters via the Photoinduced Coupling of Acylsilanes with Electrophilic Chalcogen Reagents

A novel synthesis of selenoesters and telluroesters based on the reactions of nucleophilic siloxycarbenes, which were generated by the visible-light-induced isomerization of the corresponding aroyl-, heteroaroyl-, or alkenoylsilanes, with electrophilic chalcogen reagents was developed. The use of appropriate selenides or ditellurides/Lewis acids enabled the coupling at temperatures below ambient temperature with a broad substrate scope and high functional-group tolerance. To the best of our knowledge, this is the first example of a synthetic method for selenoesters and telluroesters involving the combination of an acylanion equivalent and cationic chalcogen synthons.

Rhodium-Catalyzed Reductive Coupling of Disulfides and Diselenides with Alkyl Halides, Using Hydrogen as a Reducing Agent

[reaction: see text] We have established that RhCl(PPh3)3 catalyzes a reductive coupling of disulfides and diselenides with alkyl halides in the presence of triethylamine using hydrogen as a reducing agent. This reaction serves as a convenient new method to produce unsymmetrical sulfides and selenides from disulfides and diselenides instead of unstable and odoriferous thiols and selenols.