Regioselective iridium(iii)-catalyzed C–H cyclization using an acetylene surrogate: direct access to hydroxylated polycyclic phthalazinones

Abstract

An iridium(III)-catalyzed C–H cyclization between N-arylphthalazinones and 2-chloroacetaldehyde has been developed. This reaction provides efficient access to tetracyclic phthalazine derivatives with broad substrate scope. With the acetylene surrogate's dual electrophilic sites being selectively activated, a series of hydroxylated tetracyclic phthalazine intermediates was also prepared. Notably, the process displays excellent regioselectivity, placing substituents exclusively at the meta-position relative to the nitrogen directing group in the products.