Chiral P-lactams

Some other chiral Nylon 3 analogs have also been prepared by the same authors applying ring-opening polymerization of chiral p-lactams 84 derived from D-glyc-eraldehyde [70,71], The enantiomerically pure (2R,3R) and the racemic (2R,3R and 2S,3S) p-polyamides were obtained, and their properties compared. 

Instead, complexes with chiral chelates of the 2,2 -bipyridine (bpy) ligand could lead to asymmetric induction in the synthesis of chiral p-lactams. 

An alternative route to chiral p-lactams was provided by reactions of electron-deficient isocyanates with chiral nucleophilic alkenes such as vinyl ethers or vinyl acetates. Chlorosulfonyl isocyanate (CSI), a commonly used reactive isocyanate [34], undergoes stereospecific 5-yn-addition to alkenes. The chlorosulfonyl group can subsequently be reductively removed from the nitrogen atom. It has been shown that reactions between CSI and (Z)- and ( )-alkenyl ethers stereoselectively give cA-3,4-disubstituted azetidinones from (Z)-olefins and tmns-3,4-... 

The use of chiral sulfoxitnines 1.136 (R = Ph, Tol, Y = ArCH=N) has allowed the enantioselective synthesis of p-aminoesters after cleavage of the S-N bond by CF3COOH [510], Preliminary studies showed that the reaction of C-arenechromium tricarbonyl imines and the lithium enolate of Me2CHCOOEt gave chiral p-lactams after decomplexation with an excellent enantiomeric excess [549, 1291]. 

Amino acids are practical chiral educts (chirons), and they also steer stereoselective reactions as catalysts. Phenylalanine-controlled aldol condensations with 2-dialkyl-cyclopenta-l,3-dione give just one enantiomer (Danishefsky and Cain, 1976) Intramolecular cyclization reactions of serine yield chiral P-lactams via an active hydroxyl amide and after protection of the amino group of serine. The addition of aldehydes to cysteine produces chiral thiazolidinecarboxylic acids in quantitative yield. Aspartic and glutamic acids have been converted to... 

Chiral P-lactams prepared from a 6-imino-D-galactose derivative have been used as synthons for 6-epz-lincosamine. ... 

A route to chiral oxazolidinones reported last year (Vol. 23, p. 272) has been extended to the preparation of chiral p-lactams such as (96), which are potential precursors of carbapenems the oxazolidinones were opened reductively to P-aminoacids and then recyclized using 2-chloro-l-methyl-pyridinium iodide.72... 

AT-Carboxymethyl dipeptides are obtained by using the Strecker reaction between the amino-group of a dipeptide and an aldehyde. Chiral P-lactam components are used in a synthesis of the pentapeptide enkephalin analogue L-Tyr-D-Ala-Gly-L-Phe-L-Leu. ... 

Sekine, A., Hori, K., Ohashi, Y, Yagi, M., and Toda, R, X-ray structural studies of chiral P-lactam formation from an achiral oxo amide using the chiral-crystal environment,/.Am. Chem. Soc., Ill, 697, 1989. 

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