Rhodium-catalyzed C-H Bond Activation To Construct Cyclic Compounds

Transition metal-catalyzed C-H bond activation strategy for direct construction of C-C bonds has won the esteem in the field of organic chemistry and drug synthesis,because it is efficient and environmentally-friendly.In recent years,transition metal such as Pd,Rh,Ru and Ir catalyzed C-H functionalization have been further studied.At the same time,several synthons such as diazonone,1,4,2-oxazole-5-one and sulfoxonium ylide have also been developed by researchers.In this paper,four valuable cyclic compounds,isoquinoline,naphthol,indoloindolone and quinazoline were synthesized through rhodium-catalyzed C-H activation.The research are divided into the following four aspects.(1)A rhodium catalyzed benzimine ethyl ester and sulfoxonium ylides towards isoquinolines has been developed.As a new environmentally-friendly C2 synthon,sulfoxonium ylides took part in the dual-ortho-C-H functionalization of ethyl benzimide catalyzed by Rh(III),which undergone dehydration and cyclization with the guiding group to synthesize the fused heterocycles containing N and O atoms.(2)A rhodium-catalyzed C-H activation/cyclization of enaminones with sulfoxonium ylides toward polysubstituted naphthols has been developed.On the basis of previous work,polysubstituted naphthalenes were synthesized by the reaction of(E)-3-(dimethylamino)-1-phenyl-2-ene-1-one with sulfoxonium ylides under the catalysis of Rh(III).(3)A rhodium-catalyzed C-H aromatization/cascade cyclization of sulfoxonium ylides with anthranils toward indoloindolones has been developed.This procedure features with the formation of two C-N bonds,one C-C bond and one C=C bond in one-pot.(4)A rhodium-catalyzed 2-aryl imidazole and 3-aryl-1,4,2-dioxazol-5-one to synthesize 5-aryl imidazole [1,2-c] quinazoline has been developed.In this work,5-arylimidazole [1,2-c] quinazoline was synthesized from 2-arylimidazole as a substrate by Rh(III)catalyzed ortho-aromatization,dehydration and cyclization.