Author: Christine Salomon

The first unpaired electron placed inside a C3-symmetry P-chirogenic cluster

The Pd(3)(dppm*)(3)(CO)(n+) enantiomers (n = 2 (2), 1 (3)) were prepared either from (R,R)- or (S,S)-P-chirogenic bis(phenyl-m-xylylphosphino)methane (dppm*; 1) and Pd(OAc)(2) in the presence of CF(3)CO(2)H, CO and water (n = 2), and then by reductive electrolysis (n = 1). The stable enantiomeric [Pd(3)((S,S)-dppm*)(3)(CO)](+)˙ (3), is the first C(3)-symmetry radical-cation M-M bonded cluster, therefore the odd electron is delocalized onto the Pd(3) frame within this symmetry. The novel chiral species have been characterized by circular dichroism (CD) of both enantiomers of the Pd(3)(dppm*)(3)(CO)(2+) clusters (2) and by EPR spectroscopy for the Pd(3)((S,S)-dppm*)(3)(CO)(+)˙ paramagnetic co…

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Enantiodivergent synthesis of P-chirogenic phosphines

International audience; Several approaches for the enantiodivergent synthesis of P-chirogenic mono- and diphosphines are described, using ephedrine methodology and phosphine borane chemistry. Firstly, both enantiomers of a tertiary phosphine can be obtained starting from the same oxazaphospholidine borane complex, prepared from (+)-ephedrine, when changing the order of addition of the organolithium reagents during the synthetic pathway. The second approach is based on the chlorophosphine boranes, which react with an organolithium reagent, to afford the corresponding phosphines with inversion of configuration. In the case where the chlorophosphine borane reacts with the t-butyl lithium reage…

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The First P ‐Stereogenic 1D Coordination Polymers with the Metal Centers in the Backbone

The enantiomeric ligands (R,R)- and (S,S)-bis(o-anisylphenylphosphanyl)methane (R,R-22 and S,S-22) and (R,R)- and (S,S)-bis(phenyl-m-xylylphosphanyl)methane (R,R-23 and S,S-23; dppm*), were treated with [Cu(NCCH3)4](BF4) and AgBF4 to produce the binuclear complexes [Cu2(dppm*)2(NCCH3)4](BF4)2 or [Ag2(dppm*)2](BF4)2, respectively. Then, these complexes were used as building blocks to prepare the first P-chirogenic 1D coordination polymers {[M2(dppm*)2(dmb)2](BF4)2}n [dppm* = (R,R)-22, (S,S)-22, (R,R)-23, (S,S)-23, M = Cu, Ag, dmb = 1,8-diisocyano-p-menthane] where M is part of the backbone of the polymer chain. The isostructural nature of these new polymers with the achiral parent polymers, …

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Design of P-Chirogenic Aminophosphine-Phosphinite Ligands at Both Phosphorus Centers: Origin of Enantioselectivities in Pd-Catalyzed Allylic Reactions.

International audience; We have recently patented an unprecedented stereospecific N→O phosphinyl migration process which transforms P-chirogenic aminophosphines into phosphinites. A fine design of aminophosphine phosphinite ligands (AMPP*) derived from ephedrine and bearing a P-chirogenic center either at the aminophosphine or phosphinite moiety, was performed. The synthesis of AMPP* ligands with P-chirogenic aminophosphine moiety was based on the well-established stereospecific reaction of oxazaphospholidine-borane with organolithium reagents, followed by trapping with a chlorophosphine and borane decomplexation. Concurrently, the preparation of AMPP* ligands with P-chirogenic phosphinite …

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