Abstract

Background: Small ring nitrogen heterocycles like four membered cyclic carbamates play an important role in medicinal chemistry. The aim of the paper is to facilitate the readers with the green synthesis of carbamates. As the previous reported procedure suffer from one or more demerits such as longer reaction times, obsolete work up procedure, poor yields of the products, and the use of toxic and inflammable solvents. Therefore, we planned to develop a green procedure for the synthesis of oxazetidin-2-ones -a four membered cyclic carbamate under non-conventional energy conditions such as microwave.

Methods: A facile and convenient approach to novel 3,4-diphenyl-1,3-oxazetidin-2-ones (four membered cyclic carbamates) building blocks is described here. For the present study N-cyano(α-bromo-α-phenyl)methylanilines(I) have been used for the decarboxylation reaction employing microwave assisted organic synthesis. Their assembly is attained by N-cyano(α-bromo-α-phenyl)methylanilines (I) which undergo reductive decarboxylation to provide four membered cyclic carbamates(II) in good yield.

Results: The nitrile group gets transformed into amide derivative through microwave irradiation which subsequently suffers nucleophilic attack by alcoholic group on C-phenyl moiety to give azetidone moiety. These azetidone have been characterised through their elemental analysis, infrared, proton magnetic resonance, ¹³CNMR and high resolution mass spectra.

Conclusion: In conclusion, this paper reports a facile, simple and environmentally benign methodology for the synthesis of substituted oxazetidin-2-ones derivatives in good to excellent yields under microwave conditions by using water as a solvent. Short reaction times, simple workup procedures and mild reaction conditions are the key features of this method. Furthermore, the use of microwave makes this protocol highly efficient and economically viable.

Keywords: Azetidone, azomethines carbamates, benign solvent, microwave, N-cyano(α bromo-α-phenyl)methylaniline, oxazetidin-2-ones.