ROTATIONAL CONFORMERS OF FURAN AND THIOPHENE THIOALDEHYDE ANION RADICALS

The radical anions of the four isomeric furan and thiophene thioaldehydes have been obtained by photolysis, in an alkaline medium, of the corresponding thiols in the presence of di-tert-butyl peroxide. The same reaction also yields the four corresponding aldehyde radical anions, starting from the appropriate alcohols. The ESR spectra show that in most cases the two rotational conformers (E and Z) are present at the equilibrium. By means of appropriate methyl-substituted derivatives it has been possible to assign the structure of the two conformers. In the case of the 2-furan and 2-thiophene aldehyde anion radicals it has been also found that the conformational preference is the same as that exhibited by the corresponding molecules.