作者:István Hermecz、Ágnes Horváth
DOI:10.1016/s0040-4020(99)00548-7
日期:1999.8
Under the conditions of Vilsmeier-Haack formylation, nitrogen bridgehead ring systems containing a 6,7,8,9-tetrahydro-4H-pyrido[1,2-a]pyrimidin-4-one moiety (which can isomerize into a tautomeric 6,7-dihydro form under the reaction conditions) or a 6,7-dihydro-4H-pyrido[1,2-a]pyrimidin-4-one moiety undergo a ring transformation to afford the same nitrogen bridgehead nitrogen ring systems containing an unsaturated 4H-pyrido[1,2-a]pyrimidin-4-one moiety. Some details of the ring transformation were investigated by using deuterated and optically active derivatives. In the first step, a 7-dimethylaminomethylene-6,7-dihydro-4H-pyrido [1,2-a]pyrimidin-4-one species is formed, which is involved in the ring transformation. (C) 1999 Elsevier Science Ltd. All rights reserved.