Ring cleavage of dihydropyrimidine skeleton |
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Authors: | Hidetsura Cho Eunsang Kwon Yoshizumi YasuiSatoshi Kobayashi Shin-ichiro Yoshida Yoshio Nishimura Masahiko Yamaguchi |
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Affiliation: | a Graduate School of Science, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan b Graduate School of Pharmaceutical Sciences, Tohoku University, Japan c Research and Analytical Center for Giant Molecules, Tohoku University, Japan d WPI Advanced Institute for Materials Research, Tohoku University, Japan e Faculty of Pharmacy, Yasuda Women’s University, 6-13-1, Yasuhigashi, Asaminami-ku, Hiroshima 731-0153, Japan |
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Abstract: | The first observation of ring cleavage between positions 1 and 2 of a 1,4-dihydropyrimidine skeleton was reported upon the nucleophilic addition of 4,6-unsubstituted 1,4-dihydropyrimidine with 3 equiv of an aniline derivative or phenylhydrazine in the presence of 0.1 equiv of pyridinium p-toluenesulfonate (PPTS) in CH2Cl2; the nucleophilic reactions of 4-methyl-6-unsubstituted 1,6(3,4)-dihydropyrimidine with the same amines gave conventional substituted products at position 2. The effect of this ring opening was found to be due to the electron density of the benzene ring of a nucleophilic amine. On the other hand, aralkylamines, alkylamines, or heterocyclic amines did not cleave the skeleton. The ring-opening chemical structure was confirmed by X-ray crystallographic analysis. This characteristically different phenomenon may be due to the pattern of two CC double bonds of 1,4-DP and 1,6(3,4)-DP as well as to the effect of two substituted groups on the DP ring. |
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Keywords: | Dihydropyrimidine Ring cleavage Ring opening Dihydropyrimidine skeleton |
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