THE NAFION-H CATALYZED CYCLIZATION OF ALPHA-CARBOMETHOXY-ALPHA-DIAZOACETANILIDES - SYNTHESIS OF 3-UNSUBSTITUTED-2-INDOLINONES

Diazoanilides of type 4 were found to undergo Nafion-H catalysed cycli zation onto the aromatic ring and concomitant decarboxylation, under o ptimal conditions, to give 3-unsubstituted 2-indolinones 5 in moderate yields. Diazoanilides that possess electron-donating substituents in the aromatic moiety gave higher yields of 5 and, in one case, the pres ence of an electron-withdrawing group in the aromatic moiety did not i mpede the cyclization. In the case of the diazoanilides that possess a N-butenyl group, preferential 1,3-dipolar cycloaddition of the diazo unit onto the butenyl double bond occurred to give an unstable 1-pyraz oline which was converted, by loss of nitrogen accompanied by hydrogen migration, to dihydro-2-pyridinone derivatives. It was also found tha t substituents ortho to the amido group and/or the site of cyclization sterically retarded the cyclization.