Synthesis and biological evaluation of 4-deacetoxy-1,7-dideoxy azetidine paclitaxel analogues

Chemodivergent and Stereoselective Access to Fused Isoxazoline Azetidines and Thietanes through [3 + 2]-Cycloadditions

By combining efficient methodologies for the preparation of substituted azetines and thietes with a highly regio- and diastereoselective [3 + 2]-cycloaddition, a straightforward pathway for the synthesis of fused isoxazoline azetidines and thietanes has been designed. With minimal steps and starting from commercial sources, a new library of elaborated architectures was synthesized opening up a new class of molecules with large potential in pharmacology. Finally, a retro [2 + 2]-cycloaddition leading to substituted isoxazoles is described.

Regiodivergent Stereoselective Access to Fused Alkylideneazetidines

Following recent advances in the generalization and simplification of 2H-azetine synthesis, a regiodivergent approach to fused 2- and 3-alkylideneazetines was designed via the intermediate formation of unprecedented vinylazetine structures. Concise sequences to the latter are described from which an expected unsaturated fused ring system was isolated with very high yields and regio- and stereoselectivities by [4 + 2] cycloadditions.

Stereoselective synthesis of activated 2-arylazetidines via imino-aldol reaction

A highly stereoselective synthesis ofN-sulfinyl andN-sulfonyl azetidines have been developed involving imino-aldol reaction of ester enolates with aldimines.

A combined experimental and theoretical study of the polar [3 + 2] cycloaddition of electrophilically activated carbonyl ylides with aldehydes and imines

Numerous 2,5-diaryl-1,3-dioxolane-4,4-dicarbonitriles and 2,4-diphenyl-1,3-oxazolidine-5,5-dicarbonitriles have been synthesized by [3 + 2] cycloaddition reactions between carbonyl ylides generated from epoxides and aldehydes or imines. In contrast to the use of aldehydes (3,4,5-trimethoxybenzaldehyde, piperonal, 1-naphthaldehyde, indole-3-carboxaldehyde, furan-2-carboxaldehyde, and thiophene-2-carboxaldehyde), the reactions performed with imines (N-(phenylmethylene)methanamine, N-(1,3-benzodioxol-5-ylmethylene)propylamine, N-(1,3-benzodioxol-5-ylmethylene)butylamine, and N-(1,3-benzodioxol-5-ylmethylene)benzylamine) proceed diastereoselectively. The effect of microwave irradiation on the outcome of the reaction was studied. The mechanism of these [3 + 2] cycloaddition reactions has been theoretically investigated using DFT methods. These cycloadditions, which have one-step mechanisms, consist of the nucleophilic attack of the aldehyde oxygen or imine nitrogen on the carbonyl ylide. For the reaction with aldehydes, a back-donation effect is responsible for the unexpected reverse charge transfer found at the transition structure. The analysis of the reactivity indexes indicates that the large electrophilic character of the carbonyl ylides induces them to act as strong electrophiles in these polar [3 + 2] cycloaddition reactions.

Studies on synthesis and evaluation of quantitative structure–activity relationship of 5-[(3′-chloro-4′,4′-disubstituted-2-oxoazetidinyl)(N-nitro)amino]-6-hydroxy-3-alkyl/aryl[1,3]azaphospholo[1,5-a]pyridin-1-yl-phosphorus dichlorides

A new series of 5-[(3'-chloro-4',4'-disubstituted-2-oxoazetidinyl)(N-nitro)amino]-6-hydroxy-3-alkyl/aryl[1,3]azaphospholo[1,5-a]pyridin-1-yl-phosphorus dichlorides has been synthesized and subjected to acute antibacterial and antifungal screening studies. All the derivatives belonging to this series delineated remarkable activity as compared to standard drugs (ampicillin and clotrimazole). Compounds are quantitatively analyzed in relation to their different physicochemical parameters. Significant correlations were obtained between biological activity and polarizability parameter (MR).