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Note | Regular issue | Vol 57, No. 3, 2002, pp.501-513
Published online, 1st January, 1970
DOI: 10.3987/COM-01-9400
Amino Acid-derived 4-Alkyl-4-carboxy-2-azetidinones. New Insights into β-Lactam Ring Formation and N-Deprotection

Guillermo Gerona-Navarro, Ma Angeles Bonache, Nuria Reyero, Ma Teresa García-López, and Rosario González-Muñiz*

*Centro de Química Orgánica 'Manuel Lora-Tamayo', Instituto de Química Médica, C. S. I. C., Calle Juan de Cierva, 3, 28006 Madrid, Spain

Abstract

The preparation and N-deprotection of a series of phenylalanine-derived 2-azetidinones incorporating 2,4-dimethoxybenzyl (Dmb), 2,3,4-, 2,4,6- and 3,4,5-trimethoxybenzyl (Tmb) groups at 1 position are described. The base-promoted cyclization of the corresponding methoxy-substituted Nα-benzyl-Nα-chloroacetyl derivatives to the 1,4,4-trisubstituted azetidinones proceeded with moderate to good yields, except for the 2,4,6-Tmb analogue. In spite of the number and position of the OMe groups, N-unsubstituted β-lactams were obtained by oxidative debenzylation using potassium peroxodisulfate. Alternatively, debenzylation of Pmb, Dmb and Tmb 2-azetidinones with TFA/anisole resulted in concomitant β-lactam opening to α-benzylaspartic acid derivatives.