Structural modifications leading to changes in supramolecular aggregation of thiazolo[3, 2-𝑎]pyrimidines: Insights into their conformational features

Journal of Chemical Sciences

H Nagarajaiah¹  Noor Shahina Begum1¹ 

[1] Department of Studies in Chemistry, Bangalore University, Bangalore 560 001, India$$

关键词: Thiazolo[3;    2-𝑎]pyrimidines;    conformational analysis;    C-H…O;    C-H…N;    N-H…N;    O-H…N;    C-H$ldots$ 𝜋 and 𝜋 $ldots$ 𝜋 weak interactions.;   

DOI  :  

来源: Indian Academy of Sciences

【 摘 要 】

The compounds, 7-methyl-3,5-diphenyl-5𝐻-thiazolo[3,2-a]pyrimidine-6-carboxylic acid ethyl ester (1), 3-amino-2-cyano-7-methyl-5-phenyl-5𝐻-thiazolo[3,2-𝑎]pyrimidine-6-carboxylic acid methyl ester (2), 2-dimethylaminomethylene-7-methyl-3-oxo-5-phenyl-2,3-dihydro-5𝐻-thiazolo[3,2-𝑎]pyrimidine-6-carboxylic acid ethyl ester (3), 2-(3-cyano-benzylidene)-5-(4-hydroxy-phenyl)-7-methyl-3-oxo-2,3-dihydro-5𝐻-thiazolo[3,2-𝑎]pyrimidine-6-carboxylic acid methyl ester; with 𝑁,𝑁-dimethyl-formamide (4) and 3-ethoxycarbonylmethyl-5-(4-hydroxy-3-methoxy-phenyl)-7-methyl-5𝐻-thiazolo[3,2-𝑎]pyrimidine-6-carboxylic acid methyl ester (5) have been synthesized and their structures evaluated crystallographically. Compound 1 crystallizes in the space group 𝑃$ar{ı}$ with Z=8, with four molecules in the asymmetric unit. Compound 2 also crystallizes in the space group 𝑃$ar{ı}$ with Z=4 wherein asymmetric unit accommodates two molecules. Compound 3 belongs to 𝑃21/𝑐 with Z=4, compound 4 crystallizes in 𝑃bc21 with Z= 4 and compound 5 belongs to 𝑃$ar{ı}$ with Z=2. In all the above compounds, the aryl ring positioned at C5 of thiazolopyrimidine ring is almost perpendicular. In the case of compounds with substituted phenyl ring, aryl group-up conformation predominates. However, for compounds with unsubstituted phenyl ring, aryl group-down conformation is adopted. By varying the substituents at positions C2, C3, C6 and on the aryl at C5 in the main molecular scaffold of (1-5), we have observed significant differences in the intermolecular interaction patterns. The packing features of the compounds are controlled by C-H…O, C-H…N, N-H…N O-H…N, C-H$ldots$ 𝜋 and 𝜋 $ldots$ 𝜋 weak interactions.

【 授权许可】

Unknown