The successive reaction of phenyl vinyl thioether (1) with n-butyllithium and an electophile [E1= 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= tBuCHO, PhCHO, Me2CO,(CH2) 5CO], at− 78° C, gives after hydrolysis the corresponding methylenic diols ...