One-pot to fused pyrazoles by a double cyclization of o-alkynylaldehydes with ketones and hydrazine under metal-free condition

An efficient one-pot synthesis of fused pyrazoles has been developed. The procedure involved three components reaction of o-alkynylaldehydes 1a-s with ketones 2a-m and hydrazine under mild, metal-free reaction conditions. The desired products were obtained in one-step up to 85% yield. The molecular structure was confirmed by the X-ray crystallographic analysis. (C) 2014 Elsevier Ltd. All rights reserved.