Azapenams: An Efficient Approach to a Novel Class of β-Lactams1

Mazen Es-Sayed; Thomas Heiner; Armin de Meijere

doi:10.1055/s-1993-22347

Synlett 1993; 1993(1): 57-58
DOI: 10.1055/s-1993-22347

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Azapenams: An Efficient Approach to a Novel Class of ß-Lactams¹

Mazen Es-Sayed^* , Thomas Heiner, Armin de Meijere

^*Institut für Organische Chemie, Georg-August-Universität Göttingen, Tammannstrasse 2, D-3400 Göttingen, Germany

Abstract

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The Michael adduct of (diphenylmethylene)amine to methyl 2-chloro-2-cyclopropylideneacetate 1 is readily converted to the azidoester 2; the imino group is hydrolyzed and the primary amino group protected with a benzyloxy- or menthyloxycarbonyl group. The azide is reduced with hydrogen sulfide and the second amino group then transformed to the formamidines 5, which cyclize upon heating to the imidazolines 6 in high yields. Irradiation of (dibenzylaminocarbene)pentacarbonylchromium 7 in the presence of 6 then yields azapenams 8 in moderate to good yield as a single diastereomers. With an appropriate combination of protecting groups in the starting materials, the carboxylate function in 8b-Bn can be deprotected selectively to give the free acid 8b-H.

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Azapenams: An Efficient Approach to a Novel Class of ß-Lactams1

Azapenams: An Efficient Approach to a Novel Class of ß-Lactams¹