Selective reduction of the ester group in the 1,3-dithiol-2-(thi)one and tetrathiafulvalene series. Access to the related phosphonium salts and their Wittig reactions

Abstract In the 1,3-dithiol-2-(thi)one series, the reduction of the ester functionality into the aldehyde or the alcohol ones can be selectively achieved thanks to diisobutylaluminum hydride (DIBALH) in dichloromethane at controlled low temperature; when applied in the TTF series such a procedure only gives rise to alcohols in lower yields. From 2-thioxo-4-hydroxymethyl-1,3-dithiole 3a , the corresponding phosphonium salt 4a is readily prepared, this latter compound being a very nice synthetic intermediate in TTF chemistry thanks to its Wittig reactions. Preliminary experiments indicate that this reaction sequence can also be extended to the TTF series.