Synthesis and Reactions of Silylated and Stannylated 1,2-Azoles

Abstract

Silicon or tin 4-metalated pyrazoles and isoxazoles are synthesized by silyl- or stannylcupration from 4-haloazoles. On the other hand, 5-metalated pyrazoles are prepared by reaction of 5-unsubstituted pyrazoles with LDA and subsequent treatment with chlorosilanes and chlorostannanes. Furthermore, starting from 5-unsubstituted 4-halopyrazoles and applying both methodologies, 4,5-dimetalated pyrazoles bearing silyl groups different from trimethylsilyl or tributylstannyl groups are obtained. Some regioselective ipso-substitutions are also studied.

Key words

silylcupration - stannylcupration - silylated pyrazoles - stannylated pyrazoles - silylated isoxazoles - stannylated isoxazoles

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