New efficient synthesis of 2-substituted 5,6,7,8-tetrahydro-benzothieno[2,3-d]pyrimidin-4(3H)-ones

摘要

The carbodiimides 4, obtained from aza-Wittig reactions of iminophosphorane 3 with aromatic isocyanates, reacted with secondary amines to give 2-dialkylamino-5,6,7,8-tetrahydro-benzothieno[2,3-d]pyrimidin-4(3H)-ones 6 in presence of catalytic EtO-Na+. Reactions of 4 with phenols or ROH in presence of catalytic K2CO3 or RO-Na+ gave 2-aryl(alkyl)oxy-5,6,7,8-tetrahydrobenzothieno[2,3-d]pyrimidin-4(3H)-ones 6 in satisfactory yields. The effects of the nucleophiles on cyclization have been investigated. [References: 16]