Selective preparation and cyclization of 2-(2-hydroxyphenyl)-2-(isopropylthio)ethanols. New synthesis of 1-benzofurans
Reaction of phenols with 2-(isopropylthio)ethyl acetate activated by sulphuryl chloride afforded 2-[2-acetoxy-1-(isopropylthio)ethyl]phenols regioselectively, via[2,3]sigmatropic rearrangement of phenoxysulphonium ylides. The ortho-alkylated phenols thus obtained have been cyclized with conc. hydrochloric acid in 2-methoxyethanol to 1-benzofurans. 2-Methyl- and 2-phenyl-1-benzofurans have been prepared similarly.