New Efficient Synthesis of 2-Substituted 5,6,7,8-Tetrahydro-benzo­thieno[2,3-d]pyrimidin-4(3H)-ones

Abstract

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-tetrahydro-benzothieno[2,3-d]pyrimidin-4(3H)-ones 6 in satisfactory yields. The effects of the nucleophiles on cyclization have been investi­gated.

Key words

benzothieno[2,3-d]pyrimidin-4(3H)-ones - iminophosphorane - carbodiimide - aza-Wittig reaction - synthesis

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