An efficient method for the selective "N1" alkylation of indazoles is described. Use of alpha-halo esters, lactones, ketones, amides, and bromoacetonitrile provides good to excellent yield of the desired N1 products.

Selective Synthesis of 1-Functionalized-alkyl-1H-indazoles. -Regioselective reaction is observed using α-haloesters, lactones, ketones amides and bromoacetonitrile. 3-, 5-and 6-Substituted indazoles afford the products with high yields, while in the case of 7-substitution no selectivity is observed due to the C7-N1 peri-interaction. Products containing readily enolizable ketones are difficult to purify. The Boc-protected indazoles (XVI) afford the products (XVII) only when the amount of Cs 2 CO 3 is lowered to 1.1 equiv.