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

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.