Sulfamic Acid–Mediated, Efficient, One-Pot Synthesis of Novel 5-Substituted 1,3,4-Thiadiazol-2-ylcarbamoyl Aliphatic Amide Acid Derivatives and Facile Synthesis of Cyclic Amides

Abstract

Convenient and efficient one-pot syntheses of 5-substituted-1,3,4-thiadiazol-2-ylcarbamoyl aliphatic amide acid derivatives were described and developed using sulfamic acid catalyst. Thiosemicarbazide and substituted triethylorthoester and cyclic/alicyclic anhydride were efficiently condensed using sulfamic acid to furnish 5-disubstituted-1,3,4-thiadiazol-2-ylcarbamoyl aliphatic acid and amide derivatives in fair to good yield, which exclusively get cyclized to new cyclic amide derivatives.

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GRAPHICAL ABSTRACT

Keywords:

• Cyclic and alicyclic anhydrides
• one-pot synthesis
• sulfamic acid
• 1,3,4-thiadiazoles
• triethylorthoesters

ACKNOWLEDGMENTS

The authors thank the Council for Scientific and Industrial Research, New Delhi, India, for financial support of this research project and the principal, K.T.H.M. College, Nashik, India, for facilities.

Notes

^a A mixture of 1, 2, and 3 (1 mmol each), at rt after 25 min. SA (3 equiv) in the solvent (10 vol) was stirred at the indicated temperature.

^b Isolated yields.

^a To a mixture of 1 (5 mmol), 2 (1 equiv), and the anhydrides 3 (1 equiv) in methanol (60 ml) at 60–80 °C for 25 min and then SA (3 equiv) was added.

^b Isolated yields.

^a To a mixture of 5 (0.313 mmol), sodium acetate (2.0 equiv.), and acetic anhydrides (0.7 volume) at 65–70 °C for 5 h.

^b Isolated yields.