Martial Toffano

Synthesis and first applications of a new family of chiral monophosphine ligand: 2,5-diphenylphosphospholanes

The cyclic phosphinic acid 1-hydroxy-1-r-oxo-2c,5-t-diphenylphospholane was synthesized and resolved into enantiomers through fractional crystallization of the quinine salts. The P-phenyl, P-methyl and P-benzyl tertiary phosphine oxides were obtained from the secondary phosphine oxide, reduction of the oxides afforded the corresponding tertiary P-phenyl and P-benzyl phosphines. Hydrogenation of prochiral enamides were performed with Rh/(S,S)-1-1,2c,5-t-triphenylphospholane catalytic system. Methyl (Z)-N-acetyl dehydrocinnamate was hydrogenated to give the N-acetyl phenylalaninate in 93% ee.

Synthesis of a new class of ligands derived from isosorbide and their application to asymmetric reduction of aromatic ketones by transfer hydrogenation

A new class of β-amino alcohol and diamine ligands has been prepared from isosorbide as a chiral renewable source. The efficiency of these ligands has been evaluated for the metal-catalyzed enantioselective reduction of aromatic ketones by transfer hydrogenation, giving excellent conversion and good enantioselectivity.

Stereoselective Palladium Catalyzed Allylic Phosphination

Chiral enantiopure 2‐5‐diphenylphospholane borane 8 is an interesting nucleophile for allylic phosphination in the presence of palladium complexes to form CP bonds. A highly diastereoselective allylic phosphination reaction was realized using chiral palladium‐DACH‐naphthyl (DACH=1,2‐diaminocyclohexane) ligand as the catalyst system. The secondary phosphine‐borane complex could be classified as a NuL type nucleophile.

First isolation of enantiopure perfluoroalkylated sulfilimines and sulfoximines.

Mono-, di- and trifluoromethyl sulfilimines and sulfoximines have been isolated for the first time in enantiopure form by separation of the racemate by supercritical fluid chromatography. The electrophilic trifluoromethylating Shibata reagent has been prepared as a single enantiomer.

Kinetic resolution of pent-4-ene-1,3-diol by Pd(II)-catalysed oxycarbonylation in ionic liquids

The first example of the use of ionic liquids as reaction media in an asymmetric Pd(II)-catalysed oxycarbonylation was investigated. Based on a ligand screening, the chiral box-type ligands were successfully used in the Pd(II)-promoted bicyclisation of pent-4-ene-1,3 diol (±)-1. The kinetic resolution of (±)-1 in the presence of a chiral catalyst, p-benzoquinone and acetic acid in ionic liquids under a carbon monoxide atmosphere afforded enantioenriched 2,6-dioxabicyclo[3.3.0]octane-3-ones (S,S)-2 (80% ee) and (R,R)-2 (57% ee).

P‐Aryl‐Diphenylphospholanes and their Phospholanium Salts as Efficient Monodentate Ligands for Asymmetric Rhodium‐Catalyzed Hydrogenation

Enantiopure P‐aryl‐2,5‐diphenylphospholanes and its corresponding P‐aryl‐phospholanium salt appear as very efficient ligands for rhodium‐catalyzed asymmetric hydrogenation reaction with similar activities and enantioselectivities. The hydrogenation product was obtained in good enantiomeric excesses (up to 93 % ee) in only few minutes under an atmospheric pressure of dihydrogen. The excellent activity of the catalyst can be explained by a constant and high TOF value during the reaction.