Preparation and Oxidation of α-Phenylselanyl Esters

Alkylation and selenenylation of selenium-stabilized ester enolates have allowed the preparation of α-phenylselanyl esters 5, 7, 8 and of α,α-bis(phenylselanyl)esters 6, respectively. The competitive selenophilic reaction, leading to an allylic phenylselenide 9, was avoided in the presence of HMPA. α-phenylselanyl α,β-unsaturated esters 15 were prepared by oxidation of compounds 6 and dehydrohalogenation of β-chloroesters 17. Some other transformations: oxidation, transesterification and Grignard reaction were also studied. H2O2 oxidation of Z-esters 15 has led to stable E-α-seleninyl esters 20.