Synthesis and X-ray structure of methyl 2-oxopyrimido[2,1-b]benzothiazole-4-carboxylate from condensation of 2-aminobenzothiazole and dimethyl but-2-ynedioate

doi:10.1039/P29770001070

Paper

Synthesis and X-ray structure of methyl 2-oxopyrimido[2,1-b]benzothiazole-4-carboxylate from condensation of 2-aminobenzothiazole and dimethyl but-2-ynedioate

Published 1977 · C. Chan, J. C. Ma, T. Mak

Journal of The Chemical Society-perkin Transactions 1

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Abstract

The product from 2-aminobenzothiazole and dimethyl but-2-ynedioate has been shown by X-ray analysis to be the title compound (IIIa). Crystals of (IIIa) are monoclinic, space group P21/c, with a= 4.801(5), b= 13.68(1), c= 20.37(2)A, β= 90.44(5)°, and Z= 4. The structure was solved by direct methods and refined by full-matrix least-squares to R 0.099 for 1 931 observed photographic intensities.The molecule consists of an exocyclic carbonyl group and a methyl ester group linked to a slightly warped C6–C3NS–C4N2 ring skeleton. The carboxy-group makes a dihedral angle of 34° with the mean plane of the heterocyclic ring system. The sulphur atom participates in the molecular π-bonding, and bond-length variations in the tricyclic ring system are well accounted for in terms of simple Huckel MO theory.A reaction mechanism is suggested which involves an initial Michael addition on an acetylenic carbon by the ring nitrogen, forming an enamine with the fumarate structure. Subsequent ring-closure involving the β-methoxycarbonyl- and imino-groups leads to the formation of the product.

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Methyl 2-oxopyrimido[2,1-b]benzothiazole-4-carboxylate (IIIa) was synthesized by condensation of 2-aminobenzothiazole and dimethyl but-2-ynedioate, with a molecular

PopulationOlder adults (50-71 years)

Sample size24

MethodsObservational

OutcomesBody Mass Index projections

ResultsSocial networks mitigate obesity in older groups.

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Paper

Synthesis and X-ray structure of methyl 2-oxopyrimido[2,1-b]benzothiazole-4-carboxylate from condensation of 2-aminobenzothiazole and dimethyl but-2-ynedioate

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References

Citations

A New and Efficient Method for the Synthesis of Pyrimido[2,1- b ]Benzothiazole Derivatives

This one-pot method efficiently synthesizes pyrimido [2,1-b] benzothiazole derivatives at 60?C in 60%-72% yields without catalyst, making it a promising method for efficient synthesis of pharmaceuticals.

Synthesis and antimicrobial activity of 2H-pyrimido[2,1-b]benzothiazol-2-ones

4H-pyrimido[2,1-b]benzothiazol-2-ones show significant antimicrobial activity against Bacillus coagulans, Bacillus subtilis, Staphylococcus aureus, and Pseudomonas aeruginosa, correlated

Synthesis of 2-iminoimidazolidin-4-one derivatives by cyclization of 2-aryl-1-(4,6-dimethylpyrimidin-2-yl)guanidines with ethyl bromoacetate, dimethyl acetylenedicarboxylate, and maleic anhydride

This study demonstrates the potential of this method for the synthesis of 2-iminoimidazolidin-4-one derivatives, (E)-methyl (2-imino-5-oxoimidazolidin-4-ylidene)acetate, and (2-imino-5-oxo-imi

A REVIEW: BIOLOGICAL SIGNIFICANCES OF HETEROCYCLIC COMPOUNDS.

Heterocycles show significant biological actions as antifungal, anti-inflammatory, antibacterial, anticonvulsant, antiallergic, herbicidal, and anticancer compounds, with over 90% of new drugs containing them.