M. P. Bertrand

Memory of chirality in cascade rearrangements of enediynes.

The cascade rearrangement of chiral enediynes 1c-e, involving successively 1,3-proton shift, Saito-Myers cyclization, 1,5-hydrogen atom transfer, and intramolecular coupling of the resulting biradical, proceeded at 80 °C to form tri- and tetracyclic heterocycles possessing a quaternary stereogenic center with a very high level of memory of chirality.

En Route to (S)-Selective Chemoenzymatic Dynamic Kinetic Resolution of Aliphatic Amines. One-Pot KR/Racemization/KR Sequence Leading to (S)-Amides

A one-pot sequential process, involving a radical racemization and an enzymatic resolution, provides access to (S)-amides, from racemic amines, with ee and yields ranging from 78 to 94% and 58 to 80%, respectively.

A flexible, stereoselective dimethylzinc-mediated radical-anionic cascade: dramatic influence of additional Lewis acids.

Dimethylzinc-mediated addition of acyloxymethyl radicals to diethyl fumarate led to the highly stereoselective formation of disubstituted gamma-lactones in mean to good yields; this cascade provides a new example of a one-pot process mediated by dimethylzinc involving a tandem radical-anionic reaction; the chemoselectivity of the reaction was totally modified by additional Lewis acids.

Unprecedented Noncatalyzed anti -Carbozincation of Diethyl Acetylenedicarboxylate through Alkylzinc Group Radical Transfer

The radical carbozincation of diethyl acetylenedicarboxylate, performed at room temperature in the presence of air, leads to fumaric derivatives through a selective alkylzinc group radical transfer controlled by coordination. The total trans stereocontrol is unprecedented, carbocupration is well-known to give the reversal selectivity at low temperature, while classical radical addition methodologies lead to mixtures of isomers.

Dicobalt Hexacarbonyl Complexes of Alkynyl Imines in a Sequential Staudinger/Pauson−Khand Process. A Route to New Fused Tricyclic β-Lactams

Dicobalt hexacarbonyl complexes of alkynyl imines were allowed to react with ketenes via Staudinger reaction. Sequential [2 + 2] cycloaddition/Pauson-Khand reaction led to structurally new fused-tricyclic beta-lactams and fused-azabicyclic cyclopentenones. Chemoselectivity, scope, and limitation of the process were investigated.

Cyclizing Bifunctionnalization of Dienes by Sulfonyl Halides

Free radical sulfonyl halides addition to olefins is well documented. In the same way free radical addition to non conjugated dienes such as cis, cis -1,5 cyclooctadiene or diallylic compounds is probably one of the first known example of free radical cyclization giving yield to monomeric compounds (1) or to the cyclopolymerization process (2).