Addition of alkyllithiums to 3H-quinazoline-4-thione and various substituted quinazoline derivatives; application in synthesis

摘要

Reaction of 3H-quinazoline-4-thione (1) with two mole equivalents of an alkyllithium (z-BuLi, u-BuLi or MeLi) at -78 °C in dry THF gave the corresponding 2-alkyl-1,2-dihydro-3 W-quinazoline-4-thione (4,5 or 6) in high yield. Similarly, reactions of 4-(methylthio)quinazoline (7), 4-(ethylthio)quinazoline (8) and 4-methoxyquinazoline (9) with alkyllithiums (one mole equivalent) gave the corresponding 4-substitued 2-alkyl-1,2-dihydroquinazolines 11-18. On the other hand, blocking position 2 with a phenyl group in 4-(methylthio)-2-phenylquinazoline (20) and 4-methoxy-2-phenylquinazoline (21) resulted in reaction with two mole equivalents of alkyllithiums to give 4,4-dialkyl-2-phenyl-3,4-dihydroquinazolines 22-24.