Transition Metal Catalyzed C-H Activation For Synthesis Of Heterocyclic Compounds

Transition metal catalyzed C-H activation has attracted much attention,due to its excellent efficiency in synthetic routes and economy.Also,this transformation is widely used in the organic synthetic methodologies,natural product synthesis and medicinal chemistry.Recently,the synthesis of heterocyclic compounds is often reported using C-H bond activation.Based on the unique catalytic activity of Cp*Co(?)and Cp*Rh(?),we carried out some synthetic methods of different heterocyclic compounds,which can play a positive role for the research of C-H bond activation.The main contents of this paper include:1.The research status of Cp*Co(?)-catalyzed C-H bond activation.We briefly describe the Cp*Co(?)-catalyzed C-H bond activation based on C-C bond formation,C-N bond formation and C-X bond formation.Discussion of the reaction mechanisms and catalytic cycles for each reaction is kept to the minimum necessary to understand the outline.Cp*Co(?)catalysts sometimes exhibit unique reactivity and selectivity compared with Cp*Rh(?)and Cp*Ir(?).Such unique differences are briefly discussed.2.Co(?)catalyzed enaminone-directed C-H amidation for quinolone synthesisWe report herein the development of a Co(?)-catalyzed enaminone-directed C-H amidation method for synthetic access to quinolones,an important heterocyclic scaffold for diverse pharmaceutically active structures.The C-H coupling with dioxazolones and subsequent deacylation of an installed amide group allow consecutive C-N coupling generation of quinolones with wide-ranged compatible substituent patterns.3.Rh(?)-catalyzed N-Boc hydrazine directed C-H activation for N-amino indole synthesis.We successfully reported the synthesis of N-amino indole under Co(?)catalyst using N-Boc hydrazine as directing group coupling with diazodiester.In this reaction,we used Boc,an easily leaving group,as directing group,so that the free amino indole is synthetized in the one-pot reaction for the first time with wide-ranging compatible substituent patterns.4.Rh(?)-catalyzed N-Boc hydrazone directed C-H activation for N-amino isoquinolin-3-one.We describe in detail the Rh(?)-catalzed,N-Boc hydrazine directed C-H bond functionalization,and the synthesis of N-amino isoquinolin-3-one using diazoester as coupling partner.The reaction can be efficiently processed under acidic or basic conditions with broad substrate scope.The mechanism studies found that unprotected amino isoquinolinone is synthetized through the C-C boud coupling,C-N bond cyclization and N-Boc bond cleavage.