Acid-catalyzed rearrangement of cyclobutanols. A novel rearrangement

Abstract

The acid-catalysed dehydration-rearrangement reaction of α-thienyl cyclobutanols 3 and 4 resulted in the formation of tetrahydronaphtho[2,3-b]thiophenes 5a and 6a. The rearrangement to the linearly fused PAH system instead of the expected angularly fused system reflects α-scission of the cyclobutyl ring. A mechanism based on deuterium labelling studies is proposed to account for the product formation.