Olivier Delacroix

Pallado-catalysed hydrophosphination of alkynes: access to enantio-enriched P-stereogenic vinyl phosphine–boranes

Preliminary results dealing with the synthesis of non-racemic P-stereogenic vinylphosphine-boranes by hydrophosphination of alkynes in the presence of a chiral catalyst are reported.

Iron‐Salt‐Promoted Highly Regioselective α and β Hydrophosphination of Alkenyl Arenes

and reagents in organic synthesis. However, due to the high energy of the P H bond (E=77 kcal mol ), the reaction usually requires activation by radical initiators. Thermal-, acid-, and base-promoted reactions have also been applied, although less frequently. Metaland lanthanide-catalyzed processes were also reported recently. Whatever the method, the addition usually proceeds in an anti-Markovnikov way leading to the b adduct B (addition of the phosphorus atom to the terminal carbon atom of a terminal alkene). In contrast, the selective formation of the valuable a adduct A, with formation of a stereogenic centre, is still a challenging problem. In addition, examples of styrenic hydrophosphination are scarce. Addition to styrene was reported under basic, and radical conditions and more recently by using transition-metal catalysts (Ni, Cu). All these procedures afforded anti-Markovnikov adducts. Inexpensive and environmentally friendly iron salts have recently emerged as powerful tools in organic synthesis. Their efficiency has been demonstrated in several addition reactions to carbon–carbon double bonds (hydroamination, hydrothiolation, hydroboration, hydrosilylation, hydroarylation, and oxyphosphorylation) and during the course of our studies in the double hydrophosphination of terminal arylacetylenes. As part of our ongoing studies of the control of the regioselectivity of hydrophosphination reactions, 23] herein we report the iron-promoted hydrophosphination reaction of styrenes, which offers selective access to either the b adduct B or the a adduct A (Schemes 1 and 2).

Ph2P(BH3)Li: From Ditopicity to Dual Reactivity

A multinuclear NMR study shows that the deprotonation of diphenylphosphine-borane by n-BuLi in THF leads to a disolvated lithium phosphido-borane Ph(2)P(BH(3))Li of which Li(+) is connected to the hydrides on the boron and two THF molecules rather than to the phosphorus. This entity behaves as both a phosphination and a reducing agent, depending on the kinetic or thermodynamic control imposed to the reaction medium. Density functional theory computations show that H(2)P(BH(3))Li exhibits a ditopic character (the lithium cation can be in the vicinity of the hydride or of the phosphorus). It explains its dual reactivity (H- or P-addition), both routes going through somewhat similar six-membered transition states with low activation barriers.

First Examples of C─P Cross-Coupling Reaction of Vinyl Tosylates with Diphenylphosphine Derivative: New Access to Vinylphosphine-boranes

Vinylphosphine-borane complexes are efficiently synthesized by palladium-catalyzed C─P cross-coupling of vinyl tosylates with diphenylphosphine-borane. Both activated and unactivated vinyl tosylates are successfully used. The vinylphosphine derivatives are purified by chromatography on silica gel.

Regioselective uncatalysed hydrophosphination of alkenes: a facile route to P-alkylated phosphine derivatives

The synthesis of alkylarylphosphines is easily carried out by hydrophosphination of unactivated alkenes under mild thermal activation; gram scale amounts of products can be prepared by this simple methodology.