Regioselective synthesis of biologically interesting pentacyclic polyheterocycles by sequential thio-Claisen and AlCl3 catalyzed oxy-Claisen rearrangement of 4-(4'-aryloxybut-2'-ynylthio)-1-phenyl-1,8-naphthyridin-2(1H)-one

摘要

A number of 4-aryloxymethyl-6-phenyl-2H-thiopyrano[3,2-c][l,8]naphthyridin-5(6H)-ones were regio-selectively synthesized in 82%-95% yields by the thermal Claisen rearrangement of 4-(4'-aryloxybut-2'-ynylthio)-1-phenyl-[1,8]naphthyridin-2(1H)-ones.These products were then subjected to a second Claisen rearrangement in the presence of a Lewis acid catalyst,anhyd.AlCl3,to give hitherto unreported pentacyclic heterocycles in 75%-90% yields.The same final products were also obtained in low yield upon refluxing 4-aryloxymethyl-6-phenyl-2H-thiopyrano-[3,2-c][l,8]naphthyridin-5(6H)-ones in N,N-diethyl aniline for 12-14 h.This method was found to be more effective than thermal Claisen rearrangement.