Diastereoselective synthesis of 3-acetoxy-4-(3-aryloxiran-2-yl)azetidin-2-ones and their transformation into 3,4-oxolane-fused bicyclic β-lactams?

Organic & Biomolecular Chemistry Pub Date: 2016-11-17 DOI: 10.1039/C6OB02221A

Abstract

cis-3-Acetoxy-4-(3-aryloxiran-2-yl)azetidin-2-ones were prepared through a Staudinger [2+2]-cyclocondensation between acetoxyketene and the appropriate epoxyimines in a highly diastereoselective way. Subsequent potassium carbonate-mediated acetate hydrolysis, followed by intramolecular ring closure through epoxide ring opening, afforded stereodefined 3-aryl-4-hydroxy-2-oxa-6-azabicyclo[3.2.0]heptan-7-ones as a novel class of C-fused bicyclic β-lactams. Selective benzylic oxidation of bicyclic N-(4-methoxybenzyl)-β-lactams with potassium persulfate and potassium dihydrogen phosphate provided the corresponding N-aroyl derivatives as interesting leads for further β-lactamase inhibitor development.

Graphical abstract: Diastereoselective synthesis of 3-acetoxy-4-(3-aryloxiran-2-yl)azetidin-2-ones and their transformation into 3,4-oxolane-fused bicyclic β-lactams
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