SYNTHESIS OF 5-SUBSTITUTED 1-HYDROXYPYRAZOLES THROUGH DIRECTED LITHIATION OF 1-(BENZYLOXY)PYRAZOLE

1-Hydroxypyrazoles have been converted to 1-(benzyloxy), [(9-phenylflu orenyl)oxy], [(N,N-diethylcarbamoyl)oxy], and (-silyloxy)pyrazoles. 1- (Benzyloxy)pyrazole was lithiated selectively in the 5-position. Subse quent reaction with electrophiles gives rise to 1-(benzyloxy)pyrazole with carbon, halogen, silicon, sulfur, or tin substituents at the 5-po sition. 1-(Benzyloxy)pyrazoles could be debenzylated by hydrogen bromi de or hydrogenolysis producing 5-substituted 1-hydroxypyrazoles in hig h overall yield.