Indazole, acidity 3-lithiation

Straightforward 5-lithiation results using -BuLi with ethyl 3-mcthoxy-l -methyl-17/-pyrazol-4-earboxy late and halides, zincates, or boronic acids can thus be produced <2002SL769>. A neat device allows 3-lithiation of indazole silylation at N(2) allows the desired 3-metallation (Scheme 60) <2006EJ02417>. 

The Wittig-Horner reaction of protected 3-formylindazoles with iV-(benzyloxycarbonyl)-a-phosphonoglycine trimethyl ester has been developed as a new practical synthesis of dehydro 2-azatryptophans and amino acid derivatives <2007TL2457>. Nucleophilic addition of Grignard or lithiated reagents of 3-A -methoxy-A -methyl-amides of indazole afforded a library of 3-keto and 3-formylindazoles <2007T419>. 

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