In the last two decades, the better understanding of the mechanistic aspects of the beta-lactams' biological activity and their inhibition, and the chemical exploitation of beta-lactams as synthetic intermediates in organic chemistry, have experienced a continuous and somewhat complementary advance. A prerequisite for such a development has been the accessibility of enantiopure beta-lactams. The latter are now routinely prepared most often through the ketene-imine cycloaddition reaction, also termed the Staudinger reaction. This review accounts for the recent progress made in the asymmetric synthesis of beta-lactams (with special emphasis in the Staudinger reaction approach), as well as in their use as synthetic intermediates en route to natural products, including alpha- and beta-amino acids and peptides derived therefrom.

No abstract

Under these conditions no racemisation was observed as judged by 1H NMR and HPLC analysis of the dipeptide products. The absence of racemisation in the starting proteinogenic a-amino esters employed for each coupling reaction was verified by the Mosher test after their exposure to KCN under the reaction conditions.

1995 ketones ketones (acyclic compounds) P 0200 -089Concise General Synthesis of α,γ-Disubstituted β-Amino Ketones from β-Lactams.-Ring opening of 3,4-disubstituted N-Boc-β-lactams such as (I), promoted by aryl-Grignard reagents, yields the α,γ-disubstituted β-amino ketones (III). The same reaction starting at -78 • C and warming to room temp. leads to the corresponding carbinols of type (VI)/(IX). These are obtained in a mixture with (V) by use of primary alkylmagnesium halides in the reaction with (I), where chlorides increase the amount of β-amino ketones. The method is extended to the preparation of differently functionalized analogues and proved to represent a general access to products which may be employed as precursors of α-amino acids and polyhydroxylated nitrogen-containing compounds. -(PALOMO, C.; AIZPURUA, J. M.; GARCIA, J. M.; ITURBURU, M.; ODRIOZOLA, J. M.; J.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.