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K. Chandra Mohan, K. Ravikumar, M. M. Shetty, D. Velmurugan

Crystal and molecular structures of 4-aryl-1,4-dihydropyrimidines: Novel calcium channel antagonists

The solid-state structures of three calcium channel antagonists viz. 1,4-dihydro-6-methyl-5-N-methyl-carbamoyl-4-(3′,4′-dichlorophenyl)-2(3 H)-pyrimidinethione, C₁₃H₁₃N₃OSCl₂ (1); 1,4-dihydro-6-methyl-5-N-methyl-carbamoyl-4-(4′-methoxyphenyl)-2(3 H)-pyrimidinethione, C₁₄H₁₇N₃O₂S (2) and 1,4-dihydro-6-methyl-5-N-methyl-carbamoyl-4-(2′,4′-dichlorophenyl)-2(3 H)-pyrimidineone monohydrate, C₁₃H₁₃N₃O₂Cl₂ · H₂O (3), are reported here. The structures show that these compounds can adopt the important structural features of 1,4-dihydropyridine calcium channel blockers. In (2), the compound crystallized with three molecules in the asymmetric unit. The dihydropyrimidine ring adopts a half-chair in (1) and boat conformation in (2) and (3). The 4-aryl substituents occupies a pseudo-axial position approximately orthogonal to the plane of the dihydropyrimidine ring [95.1(2)° (1); 97.5(3)°, 79.8(2)° & 88.2(2)° (2) and 78.8(3)° (3)]. The C3 substituent, carbamoyl group, is in an extended conformation and oriented anticlinical in (1) and (3), but in (2) two molecules are anticlinal and the other one is synperiplanar, respectively. Intra- and inter- molecular interactions may be influencing the orientation of the C3 carbamoyl group. The 2-chlorophenyl substituent in (3) is in the axial synperiplanar orientation.

Zeitschrift für Kristallographie, Oldenbourg Wissenschaftsverlag

Print ISSN: 0044-2968
Volume: 218, 01/2003
Pages: 046

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