Ultrasound mediated synthesis of ecofriendly zinc chalcogenates in "on water conditions"

Nucleophilic Selenium is a convenient strategy for the functionalization of organic substrates having electrophilic character. Among all the methods developed for their preparation, the reduction of the corresponding diselenides represents the most versatile procedure. Using these protocols selenolates were usually prepared in situ using atom expensive reducing agents such as NaBH4, LiAlH4, or metals (Na, Li) or metal hydride (NaH). We recently reported that zinc can be efficiently used to reduce Se-halogen bond affording bench stable regents such as PhSeZnCl that showed a strong rate acceleration in “on water” conditions for a number of reactions: alkyl, aryl, vinyl and acyl substitutions, ring-opening reactions of epoxides and aziridines and Michael type addition.  We report now the use of Ultrasound irradiation for the oxidative insertion of zinc into Se-Se bond and the formation of the nucleophilic reagent PhSeZnSePh  as a green strategy to avoid the use of useless halogen and increase the atom economy of the selenenylating species.