Regioselective lithiation of 1‐benzylpyrazole derivatives: Synthesis of amides derived from pyrazole

Abstract

A series of brominated 1‐benzylpyrazoles were deprotonated at the pyrazole 5‐position or the benzylic position on treatment with lithium diisopropylamide in tetrahydrofuran at low temperature. The obtained organolithium intermediates were subjected to reaction with Me3SiCl, t‐BuNCO, ClCONEt2 or ClCON(i‐Pr)2 affording the respective silanes or amides after hydrolysis.