The position of the carbonyl-stretching bands in the i.r. spectra of the desaurins, 2,4-bis(acylmethylene)- and 2,4-bis(carboxymethylene)-1,3-dithetane derivatives, establishes that there is a strong interaction between the sulfur atoms and the carbonyl groups. This is considered to involve mainly conjugative interaction rather than interaction through space, although the latter may account for the abnormally weak intensity of the carbonyl-stretching bands. These bands are split in the case of several desaurins and related compounds, and evidence has been obtained in one case that the splitting is due to Fermi resonance. The u.v. spectra of the desaurins and related compounds also indicate a strong conjugative interaction between the sulfur atoms and the carbonyl groups.
Ring transformation reactions of 1-substituted 2(1H)-pyrimidinones and related compounds with active methylene compounds.