Nucleophilic replacement of the tert-butylsulfonyl group in the thiophene series. IX

Abstract

The conditions for dimethylation of tert-butyl-2-thienylsulfone at positions 3 and 5, in 60–70% yield, are determined. In 5-tert-butyl-sulfonylthiophene-2, 4-dialdehyde, the tert-butylsulfonyl group readily undergoes nucleophilic replacement by RS and RO groups. In the case of 3-tert-butylsulfonylthiophene-2, 5-dialdehyde, treatment with nucleophilic reagents does not lead to replacement, and only a hemiacetal is formed from one of the aldehyde groups.