Rhodium-catalyzed Coupling-reaction Of Carbenoids With Enynes And Pyridines

The cycloaddition reaction of unsaturated enyne compounds provides an efficient chemical conversion platform for the synthesis of complex molecules,and is widely used in the synthesis of natural products and drug molecules with polycyclic fused systems.In this paper,a Rh(I)-catalyzed coupling cyclization reaction of enyne and diazo was developed.This reaction can quickly obtain alkenyl substituted bicyclic[3.1.0]hexane with various functional groups,and the substrate expansion of diazo can be extended to acceptor/acceptor or donor/acceptor diazo.The mechanism study demonstrating that the coupling reaction between the Rh catalyst and the alkynyl group in 1,6-enynes produces rhodium cyclobutene and rhodium carbene species first.Subsequently,the rhodium carbene and the olefin functional group form an alkenyl nitrogen heterocyclic product by cascade intramolecular cycloaddition/reductive elimination.Pyridine structures are ubiquitous in many biologically molecules and drugs.Therefore,selective C–H functionalization at specially point of pyridine is of great research significance in organic synthesis.This paper initially explores the Rh(II)-catalyzed cross-coupling reaction between pyridine and the carbene precursor triazole,in which the carbenoid can be inserted into the C3 position of pyridine with high selectivity to construct a trisubstituted olefin biaryl compounds.The undirected alkenylation of Csp~2-H at the 3-position of pyridine was achieved,and the feasibility of the reaction between pyridine and carbene precursor triazole was also demonstrated.