98050-76-1Relevant academic research and scientific papers
X-RAY CRYSTALLOGRAPHIC ANALYSIS OF TAUTOMERIC DIHYDROPYRIMIDINE DERIVATIVES
Cho, Hidetsura,Hamamoto, Yoshihiro,Shima, Keiyuu,Taira, Zenei
, p. 6429 - 6436 (2007/10/02)
X-ray crystallographic analysis of various dihydropyrimidine tautomers was carried out. 4-(2-chlorophenyl)-5-ethoxycarbonyl-2,6-dimethyldihydro-pyrimidine 1 exists in an electron-localized 1,4-dihydro form with a flat boat conformation in the crystalline state. 6-Chloro-4-(2-chlorophenyl)-5-ethoxycarbonyl-2-methyldihydropyrimidine 2 synthesized as 1/2 HCl salt after extractive work-up under basic conditions consists of two different molecules with Cl atoms; the molecules of electron-localized 1,4-dihydro form 2a and electron-delocalized form 2b.Both forms are linked by hydrogen bonding around the center of symmetry in the unit cell.X-ray analysis of compound 2c prepared by the addition of excess HCl-Et2O to a solution of compound 2 exhibits an electron-delocalized structure of different molecular arrangement.
Synthesis of Novel Dihydropyrimidines and Tetrahydropyrimidines
Cho, Hidetsura,Shima, Keiyuu,Hayashimatsu, Mariko,Ohnaka, Yoshiko,Mizuno, Akira,Takeuchi, Yumi
, p. 4227 - 4230 (2007/10/02)
Condensation of alkyl 2-acetyl-3-aryl-2-propenoate with acetamidine, benzamidine, guanidine, or 1,1-dimethylguanidine followed by dehydration of the resulting compound 2 with p-TsOH or Al2O3 gave 1,4(3,4)-dihydropyrimidine 3.Regioselective alkoxycarbonylation, acylation, and alkylation of compound 3 with alkyl chloroformate, acyl halide, or alkyl halide in the presence of NaH afforded the series of novel N-substituted 3,4-dihydropyrimidines 4, 5, and 6 in good yield.Stereoselective NaBH4 reduction of the 3,4-dihydropyrimidine hydrochloride 4 provided a singlestereoisomer of 1,2,3,4-tetrahydropyrimidine 7 whose stereochemistry was assigned as cis by X-ray crystallographic analysis.Conversely, the same reduction of the HCl salts of 3 or 6 gave a cis-trans mixture of tetrahydropyrimidines 8.
