Studies of heterocyclic compounds. Part IX. Formylation of 6a-thiathiophthens

Abstract

6a-Thiathiophthen and 2,5-dideuterio-6a-thiathiophthen undergo formylation with NN-dimethylthioformamidephosphoryl chloride at position 3. Formylation of 2-t-butyl-6a-thiathiophthen and 5-deuterio-2-t-butyl-6a-thiathiophthen occurs at position 4. The position of formylation was established by comparative ¹H n.m.r. and mass spectral studies. 2-Methyl- and 2,5-dimethyl-6a-thiathiophthen condensed with NN-dimethylthioformamide at their reactive methyl groups, giving enamines. The i.r. spectra of formyl-6a-thiathiophthenes indicate that the 6a-thiathiophthen nucleus is electron-releasing at the 3(4)-position. Formyl-6a-thiathiophthens were reduced by sodium borohydride to the corresponding hydroxymethyl-6a-thiathiophthens, and were partially desulphurised by mercuric acetate to 3-diformylmethylene-3H-1,2-dithioles.