32357-21-4Relevant articles and documents
Dithio and thiono esters, 64: Attempted synthesis of bis(alkylthio)-orthoquinodimethanes from dithiobenzoates
Hartke, Klaus,Bien, Notker,Massa, Werner,Wocadlo, Sigrid
, p. 1159 - 1166 (2007/10/03)
o-Alkyl substituted dithiobenzoates 3 are S-methylated with trimethyloxonium tetrafluoroborate to form the stable bis(alkylthio)arylmethylium tetrafluoroborates 4. Their deprotonation with LiHMDS takes place either at the o-alkyl groups to form the postulated o-quinodimethanes 5 as intermediates or at the SMe groups to give the thiocarbonyl ylides 7. Both intermediates dimerize to furnish either the dibenzo[a,e]cyclooctenes 6 or the 1,4-dithianes 8/9. Their trapping with N-phenylmaleimide (10) leads to the formation of the cycloadducts 11 or 12. The structure of 8e was confirmed by X-ray analysis. p-Substituted dithiobenzoates 13 show a similar reaction sequence. Their bis(methylthio)arylmethylium salts, however, are only deprotonated at one of the SMe groups to give the 1,4-dithianes 15/16. Sterically crowded 1,4-dithianes (e.g. 8d,e/9d,e) rearrange with traces of acid to the ring opened stilbenes 18 and 19. VCH Verlagsgesellschaft mbH, 1996.
