Abstract
The reaction of 2-methoxycarlmethylen-l,2-dihydro-4H-pyrido[2,3-b]pyrazin-3-one(5) with hydrazine hydrate and ethylenediamine gave 2-hydrazinocarbonylmethylene-1,2-dihydro-4H-pyrido[2,3-b]pyrazin-3-one(6) and 2-aminoethylcarbamethylene-1,2-dihydro-4H-pyrido[2,3-b]pyrazin-3-one(7), res-pectively. The reaction of compound 6 or 7 with substituted benzaldehydes or heteroaryl aldehydes afforded pyrido[2,3-b]pyrazines(8-13). Some pyrin the enamine, methylene imine and enaminol forms in solution. The tau-tomer ratios were determined by the H NMR.
2-Methoxycarbonylmethylene-1,2-dihydro-4H-pyrido[2,3-b]pyrazin-3-one(5)을 hydrazine hydrate와 ethylenediamine을 반응시켜 2-hydrazinocarbonylmethylene-1,2-dihydro-4H-pyrido[2,3-b]pyrazin-3-one(6)과 2-aminoethylcarbamoylmethylene-1,2-dihydro-4H-pyrido[2,3-b]pyrazin-3-one(7)을 각각 합성하였다. 화합물 6 또는 7을 치환 벤즈알데히드류 및 헤테로아릴 알데히드류와 반응시켜 pyrido[2,3-b]pyrazin류(8-13)를 각각 합성하였다. 몇가지 pyrido[2,3-b]pyrazin은 용액에서 enamine형,methylene imine형, methylene imine형,enaminol형 사이에 토토머화 현상을 나타내었는데, 이들의 토토머 비는 1H NMR로서 측정하였다.