Phenyl vinyl thioether: A convenient source of the ethylene 1,1-dianion

Abstract

The successive reaction of phenyl vinyl thioether (1) with n-butyllithium and an electrophile [El=PhCHO, (CH2)4CO, (CH2)5CO] in THF at −78°C gives, after hydrolysis, the expected methylenic hydroxy thioethers (2). Deprotonation of 2 with n-butyllithium followed by a DTBB-catalysed lithiation and reaction with a second electrophile [E2=1BuCHO, PhCHO, Me2CO, (CH2)5CO], also at −78°C, gives after hydrolysis the corresponding methylenic 1,3-diols 3. When carbon dioxide is used as the second electrophile, the expected methylenic hydroxy acid 3cd is isolated. The whole process can be performed in a one-pot manner without isolation of the intermediates 2.