Asymmetric Lewis acid-catalyzed 1,3-dipolar cycloadditions

Highly tuned, one-point binding chiral iron and ruthenium complexes selectively coordinate and activate α,β-unsaturated aldehydes and ketones toward asymmetric catalytic Diels-Alder cycloaddition reactions. Here we focus on the application of these transition-metal Lewis acids to asymmetric catalytic 1,3-dipolar cycloaddition reaction between enals and cyclic and acyclic nitrones as well as aryl nitrile oxides to give isoxazolidines and isoxazolines, respectivel

Síntesis asimétrica de heterociclos polisustituidos y aplicación a la síntesis de productos naturales

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid. Facultad de Ciencias. Departamento de Química Orgánica. Fecha de lectura: 01-07-200

Asymmetric Lewis Acid-Catalyzed 1,3-Dipolar Cycloadditions

Highly tuned, one-point binding chiral iron and ruthenium complexes selectively coordinate and activate α,β-unsaturated aldehydes and ketones toward asymmetric catalytic Diels-Alder cycloaddition reactions. Here we focus on the application of these transition-metal Lewis acids to asymmetric catalytic 1,3-dipolar cycloaddition reaction between enals and cyclic and acyclic nitrones as well as aryl nitrile oxides to give isoxazolidines and isoxazolines, respectively

Stereocontrolled Access to Isoprostanes via a Bicyclo[3.3.0]octene Framework

International audienc

Total Synthesis of 15-D2t- and 15-epi-15-E2t-Isoprostanes

International audienceThe first total synthesis of 15-D2t-isoprostane is described. (-)-(9S,15S)-15-D2t-IsoP 1 and (+)-(11R,15R)-15-epi-15-E2t-IsoP 2 have been obtained in 15 steps from orthogonally protected enantiopure bicycle 3. Key features include an easy introduction of the cis side chains via ozonolysis, a highly enzymatic chemical differentiation of a non-meso-1,5-diol, and the use of a common synthetic intermediate allowing a stereodivergent approach to the target mols

Chiral ruthenium Lewis acid-catalyzed nitrile oxide cycloadditions

The synthesis of the chiral ligand (R,R)-BIPHOP-F is detailed. Its coordination to a cationic cyclopentadienyl ruthenium fragment generates [Ru (acetone)(R,R)-BIPHOP-F)Cp][SbF6], a transition metal Lewis acid that catalyzes the [3+2] dipolar cycloaddition reaction between aryl nitrile oxides and α,β-unsaturated aldehydes to give chiral 2-isoxazolines with yields of 43–98% and asymmetric purity of 60–93% ee. The stereochemistry of the major enantiomer is S, consistent with an approach of the nitrile oxide to the Cα-Si face of the enal in the anti-s-trans conformation in the catalyst site

Lipase-catalyzed regioselective monoacetylation of unsymmetrical 1,5-primary diols

International audienceLipase B from Candida antarctica (CALB) has been selected as the most suitable enzyme to catalyze the regioselective monoacetylation of 1,5-diol isoprostane intermediate, using vinyl acetate as an acyl transfer reagent in THF.We next applied this reaction on linear 2-substituted, 2,20-disubstituted-1,5- pentanediols, and cyclic 2,3-disubstituted-1,5-pentanediols. To rationalize the regioselectivity observed, molecular docking simulations were performed