Synthesis and reactions of silylated and stannylated 1,2-azoles

Silicon or tin 4-metalated pyrazoles and isoxazoles are synthesized by sily l- or stannylcupration from 4-haloazoles. On the other hand, 5-metalated py razoles are prepared by reaction of 5-unsubstituted pyrazoles with LDA and subsequent treatment with chlorosilanes and chlorostannanes. Furthermore, s tarting from 5-unsubstituted 4-halopyrazoles and applying both methodologie s, 4,5-dimetalated pyrazoles bearing silyl groups different from trimethyls ilyl or tributylstannyl groups are obtained. Some regioselective ipso-subst itutions are also studied.