Heterocyclization of N-propenyl-substituted phenothiazines and phenoxazines using electrophiles in an anhydrous medium
作者:E. E. Sirotkina、A. I. Khlebnikov、O. A. Napilkova
DOI:10.1007/s10593-009-0219-5
日期:2008.12
10-Propenylphenothiazine reacts with a catalytic amount of BF3 center dot Et2O in dry ethyl acetate via intramolecular heterocyclization of an intermediate dimeric cation to give mainly 1-ethyl-2-methyl-3-(phenothiazin-10-yl)-2,3-dihydro-1H-pyrido[3,2,1-k,l]phenothiazine and a minor product through fission of phenothiazine which is 1-ethyl-2-methyl-1H-pyrido[3,2,1-k,l]phenothiazine. Under similar conditions 10-propenylphenoxazine gave an oligomer (degree of polymerization 4.4) and the minor product 1-ethyl-2-methyl-1H-pyrido[3,2,1-k,l]phenoxazine likely formed similarly to the phenothiazine analog from the corresponding product of intramolecular heterocyclization (the latter not being observed in the reaction mixture).