Mn(III)-BASED OXIDATIVE CYCLIZATION OF 2-((2-ARYLAMINO)ETHYL)MALONATES: SYNTHESIS OF QUINOLINES VIA TETRAHYDROQUINOLINEDICARBOXYLATES

摘要

The synthesis of quinolines from aniline derivatives via the Mn(III)-based oxidative cyclization of 2-(2-(arylamino)ethyl)malonates is described.The 2-(2-(arylamino)ethyl)malonates were prepared in two steps from the substituted anilines.The cyclization of nineteen arylaminoethylmalonates protected by the N-acyl and N-alkoxycarbonyl groups easily proceeded in the formal 6-endo mode regardless of the presence of halo,methyl,and methoxy groups on the aromatic ring,and the corresponding tetrahydroquinolinedicarboxylates were produced in high yields except for the 2,4-dimethoxyphenyl-substituted aminoethylmalonate which occurred by ipso-cyclization.The tetrahydroquinolinedicarboxylate could be transformed into quinoline via decarboxylation and deprotective hydrolysis.The characteristic phenomenon in the NMR spectrum of the tetrahydroquinolinedicarboxylates is also discussed.