Silver–Catalyzed C–C Bond Insertion Of Alkynyl Carbenes

The selective activation of C–C bonds is one of the most important fields in organic chemistry,which enables the preparation of organic compounds that are difficult to obtain by other methods by altering the carbon skeleton.Among existing C–C bond cleavage transformations,the use of diazonium compounds or their precursors to insert carbon atoms into C–C bonds is a powerful means to build highly selective and complex molecules,a strategy that has been successfully applied to natural products in full synthesis.Using diazo compounds as carbene precursors to react with cyclic/acyclic ketone derivatives can only yield sp~3-hybridized carbon homologous products.However,the C–C bond insertion reaction studies of carbon homologation products with sp~2 hybridization are still unknown.Since alkynylcarbene precursors were first reported in the 1970s,alkynylsulfonyl hydrazones have rarely been used as alkynylcarbene precursors.The main problem is that intramolecular cyclization easily occurs to form pyrazoles.Therefore,it is necessary to develop a simple,efficient,and system-compatible alkynylcarbene precursor.Here,we carried out the silver catalyzed C–C bond insertion reaction between alkynyl-N-nitrobenzene sulfonylhydrazone and 1,3-dicarbonyl compounds for the first time,and successfully inserted alkynyl carbene intoβ-C–C bond of ketone carbonyl group and undergo one-step isomerization to obtain diene ketone derivatives with sp~2hybridization.We use alkynyl-N-nitrophenyl sulfonyl hydrazone as the precursor of alkynyldiazo to solve the problems of explosive and unstable diazo compounds and intramolecular cyclization of alkynylbenzene sulfonyl hydrazone.The method developed in this paper shows good functional group tolerance and a wide range of substrates,and the reaction has also been successfully used in the preparation of trisubstituted bienone compounds in gram grade,which proves the magnification of the method.The final product is transformed into natural product molecules,demonstrating its application value in organic synthesis.