A unique gold(I)-catalyzed 5-endo-dig cyclization/aerobic oxidationcascade strategy from 1,5-enyne substrates with molecular oxygen as the oxidant to yield the indenone was described. The reaction mechanism was studied by heavy atom labelling and some related experiments. This method was applied to the formal total synthesis of isoprekinamycin.
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.