Thiophene chemistry—IX Preparation and dealkylation of 5-substituted 2-t-butoxythiophenes

Different substituents have been introduced into the 5-position of 2-t-butoxythiophene and by subsequent acid-catalyst dealkylation the corresponding hydroxythiophenes (or their different tautomeric forms) have been isolated in high yields. By NMR, IR and UV-spectroscopy the constitution and the composition of the different tautomeres have been determined. The reaction between carbonyl compounds and 5-t-butoxy-2-thiophenelithium gives carbinols, which upon heating with p-toluenesulphonic acid yielded 5-methylene-3-thiolen-2-ones.