4-Amido-3,4-dihydro-2H-1-benzothiopyran-3-ols and their sulphoxide and sulphone derivatives—cromakalim analogues

Abstract

The racemic 6-methylbenzothiopyranols 26–28 and the dehydrated analogues 6, 9 and 25 of the smooth muscle relaxant cromakalim (±)-1 have been synthesised with the sulphur in different oxidation states. Problems of ring contraction to benzothiophene derivatives encountered during the attempted direct preparation of the sulphide 27 were overcome by protection as the sulphoxide 26 and subsequent deprotection.