A new approach to the stereoselective synthesis of trans-3-carbamoyl-β-lactam moieties

Abstract

Optically active 1,4-disubstituted-3-carbamoyl-azetidinones are synthesized from 5-[(N-arylamino)(hydroxyl)methylene]-2,2-dimethyl-1,3-dioxa-4,6-diones and chiral aldimines via thermal generation of carbamoyl ketenes and subsequent [2+2] cycloaddition.

Synthetic return of the Meldrum’s acid. 2,2-dimethyl-1,3-dioxane- 4,6-dione assisted formation of tetrahydroquinolin-2-one derivatives. Short synthetic pathway to the biologically useful scaffold

“…In the current paper, taking into consideration our experience with the synthesis of pyridones together with our knowledge about the application of Meldrum's acid [25][26][27][28][29][30] in synthesis and considering of available literature we would like to present a new approach for preparation of 2-pyridones.…”

Access to 2-Oxoazetidine-3-carboxylic Acids Derivatives via Thermal Microwave-Assisted Wolff Rearrangement of 3-Diazotetramic Acids in the Presence of Nucleophiles

“…Most synthetic approaches to amides and esters of 2-oxoazetidine-3-carboxylic acids reported in the literature are based on the construction of the β-lactam ring (Scheme 1). The main methods include the [2+2] cycloaddition of acyl ketenes, generated by various methods, with imines [11][12][13][14] and the Wolff rearrangement of γ-amino-α-diazo-β-keto esters followed by intramolecular cyclization. [15,16] Additionally, the manganese(III)-promoted cyclization of N-alkenyl malonamides [17,18] and the Cu(I)-catalyzed reaction of propiolic acid derivatives with nitrones (Kinugasa reaction) [19][20][21] should also be mentioned, as well as intramolecular C-H insertion using diazo monomalonamides under the action of various catalysts which is a very efficient method for preparing β-lactam esters.…”