Swapping Copper‐Catalytic Process: Selective Access to Pyrazoles and Conjugated Ketimines from Oxime Acetates and Cyclic Sulfamidate Imines

Abstract

A powerful CuCl-catalyzed sequential one-pot reaction of aryl methyl ketoxime acetates with cyclic Nsulfonyl imines followed by elimination in the presence of base is reported. This hydrazine-free method conveniently makes CÀ C and NÀ N bonds via a radical cleavage of the NÀ O bond, delivering a special class of C3-hydroxyarylated pyrazoles in good yields. Surprisingly, while employing CuI as a catalyst instead of CuCl, the reaction proceeds through a non-radical pathway which embodies a new tactic for the high-yielding access to value-added conjugated N-unsubstituted ketimines. Moreover, additive-free approach to sulfamidate-fused-pyrazoles was achieved by successfully catalyzing addition and oxidative NÀ N bond-making reactions by CuI and CuCl, respectively. Significantly, our novel technique could convert the prepared ketimines into the pharmacologically recognized 6H-benzo[c]chromene frameworks.