Regioselective Synthesis of Silylated Pyrazolines and Indazolines by Reaction of Pyrazolium and Indazolium Salts with Silyllithium Reagents

Abstract

Abstract Pyrazolium salts react with dimethylphenylsilyl‐ and tert ‐butyldiphenylsilyllithium to give, in general, only one of the two possible 5‐silyl‐3‐pyrazolines. On the other hand, indazolium and isoindazolium salts lead to 3‐silylindazolines and occasionally to compounds resulting from the opening or expansion of the heterocyclic ring. All of these compounds are interesting synthons in organic chemistry. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)