REGIOSELECTIVE SYNTHESIS OF HETEROCYCLES FROM LOHEX-2-ENYL-4-HYDROXY-1-METHYLQUINOLIN-2-(1H)-ONE

clohex-2-enyl-4-hydroxy-1-methylquinolin-2(1H)-one (5) reacts with pyr idine hydrotribromide in CH2Cl2 at 0-5 degrees C for 0.75h to give a f uro fused heterocycle 6 in 96% yield. Product 6 on treatment with KOH- EtOH eliminates HBr to give compound 8 which on treatement with Pd-C i n refluxing diphenyl ether for 0.5 h furnishes benzofuro[3,2-c]quinolo ne 9 in 90% yield. Substrate 5 on sequential treatment with Ac2O-AcONa and Br-2/AcOH followed by KOH-EtOH, however produces bicyclic product 7 in excllent overall yield. Substrate 5 reacts with 1 equivalent of m-chloroperbenzoic acid in refluxing benzene to furnish bicyclic heter ocycle 12 in 80% yield and with cold cone. H2SO4 at 0-5 degrees C for 2h generates the bicyclic heterocycle 14 in 90% yield.