Synthesis of 5-Substituted 1-Hydroxypyrazoles through Directed Lithiation of 1-(Benzyloxy)pyrazole
摘要:
1-Hydroxypyrazoles have been converted to 1-(benzyloxy), [(9-phenylfluorenyl)oxy], [(N,N-diethylcarbamoyl)oxy], and (-silyloxy)pyrazoles. 1-(Benzyloxy)pyrazole was lithiated selectively in the 5-position. Subsequent reaction with electrophiles gives rise to 1-(benzyloxy)pyrazole with carbon, halogen, silicon, sulfur, or tin substituents at the 5-position. 1-(Benzyloxy)pyrazoles could be debenzylated by hydrogen bromide or hydrogenolysis producing 5-substituted 1-hydroxypyrazoles in high overall yield.
Synthesis of 5-Substituted 1-Hydroxypyrazoles through Directed Lithiation of 1-(Benzyloxy)pyrazole
作者:Per Vedso、Mikael Begtrup
DOI:10.1021/jo00121a017
日期:1995.8
1-Hydroxypyrazoles have been converted to 1-(benzyloxy), [(9-phenylfluorenyl)oxy], [(N,N-diethylcarbamoyl)oxy], and (-silyloxy)pyrazoles. 1-(Benzyloxy)pyrazole was lithiated selectively in the 5-position. Subsequent reaction with electrophiles gives rise to 1-(benzyloxy)pyrazole with carbon, halogen, silicon, sulfur, or tin substituents at the 5-position. 1-(Benzyloxy)pyrazoles could be debenzylated by hydrogen bromide or hydrogenolysis producing 5-substituted 1-hydroxypyrazoles in high overall yield.