Hideyuki Ikehira

n-Butyl-lithium-induced cleavage of several dithioacetals derived from diaryl ketones

The reaction of 2,2-diaryl-1,3-dithiolanes and -1,3-dithianes, and diaryl ketone di-n-propyl dithio-acetals with n-butyl-lithium in tetrahydrofuran followed by alkylation with alkyl halides gives 1-n-butylthio-2-(1,1-diarylalkylthio)ethanes and -3-(1,1-diarylalkylthio)propanes, and 1,1-diarylalkyl n-propyl sulphides, respectively. The process probably involves S-addition of an n-butyl anion with simultaneous cleavage of the bond between the sulphur atom and the adjacent carbon atom giving an intermediate anionic species, which is then alkylated by the alkyl halide.

A new 1,2-rearrangement of carbon from sulphur to carbon in 2,2-diaryl-1,3-dithianes

2,2-Diaryl-1,3-dithianes undergo with lithium di-isopropylamide in tetrahydrofuran a Wittig-type rearrangement to form the anions of the 2,2-diaryltetrahydrothiophene-3-thiols which are further converted into bis(2,2-diaryltetrahydrothiophen-3-yl) disulphides by treatment with aqueous ammonium chloride and after subsequent autoxidation.