Structure of the acetylation and formylation products of 2-tert-butyl-5-methylthiophene and 2,5-di-tert-butylthiophene

Abstract

1. It was shown that, in the formylation, acetylation, and bromination of 2-tert-butyl-5-methylthiophene, the new substituent enters the 4-position (the β-position next to the methyl). 2. It was shown that, in the acetylation of 2,5-di-tert-butylthiophene in presence of stannic chloride, no migration of the tert-butyl group occurs. 3. It was shown that it is possible to prepare thiophenecarboxylic acids containing α-alkyl radicals (methyl, tert-butyl) by the simultaneous action of iodine and pyridine on the corresponding ketone and subsequent splitting of the resulting pyridinium salt with alkali. 4. The following were prepared for the first time: 5-tert-butyl-2-methyl-3-thiophenecarboxylic acid, 2,5-di-tert-butyl-3-thiophenecarboxylic acid, and 3-bromo-5-tert-butyl-2-methylthiophene.