Methodologies, tools for synthesis - Organoboron chemistry

Boron has become an essential element in modern synthetic chemistry, mainly due to
• the various and efficient methods available for the introduction of a boron substituent into carbon frameworks, mostly with control of the stereochemistry.
• the wide range of transformations of the C-Boron bond into a C-Carbon or C-heteroatom bond (Suzuki, Cham-Lam, Petasis, ……) that open the route to the synthesis of a large variety of structurally and functionally diverse compounds.
Impressive advances have also been made in the use of organoboron compounds as enzyme inhibitors, in molecular recognition, materials science, and catalysis.

In recent years, our research interests have focused on four main topics:

which is capable of providing a wide range of homoallylic alcohols or amines with excellent control of the relative and absolute configurations of the created stereocenters. We have proposed several original methods to access to functionalized allylboranes and study their reactivity.

The use of 3-boronoacrolein esters and alkyl enol ethers for the inverse electron demand hetero-[4+2] cycloaddition, catalyzed by chromium complexes, was shown to be very efficient for synthesis of hydroxyalkyl dihydropyrans, a common substructure of many biologically important molecules and natural products.

For applications in natural products synthesis, see: Multistep or total synthesis

Collaboration with A. Whiting, Durham, GB.

The nature of the substituents of these easily accessible building blocks enabled the diversity-oriented synthesis of an array of cyclic and bicyclic heterocycles with high skeletal and functional diversity.

Collaboration with J. Crassous, OMC, ISCR, Rennes.

Enantiopure carbo[6]helicenyl boronates were synthesized using a photocyclization reaction as the key step. These compounds were further converted to various amino derivatives using copper-catalyzed azidation or amination and reductive alkylation of benzylazide by a helicenyl dichloroborane. Asymmetric Petasis condensation with glyoxylic acid and morpholine controlled by the helical chirality afforded the corresponding amino esters.

Collaboration with G.V. M. Sharma and S. Ghosh, IICT, Hyderabad, India.

These compounds have been used as starting material for the syntheses of 1-amino-1H-indenes, unsaturated amino esters, polysubstituted isoquinolines and related fused pyridines.

Collaboration with J.-B. Sortais, LCC Toulouse and C. Darcel ISCR Rennes.

The catalytic system based on Fe(OTf)2 (2.5 mol%) and DABCO (1 mol%) selectively promotes the dehydrogenative borylation of both aromatic and aliphatic terminal alkynes to afford alkynylboronate derivatives in the presence of 1 equiv. of pinacolborane at 100 °C in toluene.

For more information : Fabienne Berrée, François Carreaux