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''P''-Chiral phosphines are organophosphorus compounds of the formula PRR′R″, where R, R′, R″ = H, alkyl, aryl, etc. They are a subset of chiral phosphines, a broader class of compounds where the stereogenic center can reside at sites other than phosphorus. P-chirality exploits the high barrier for inversion of phosphines, which ensures that enantiomers of PRR'R" do not racemize readily. The inversion barrier is relatively insensitive to substituents for triorganophosphines. By contrast, most
''P''-Chiral phosphines are organophosphorus compounds of the formula PRR′R″, where R, R′, R″ = H, alkyl, aryl, etc. They are a subset of chiral phosphines, a broader class of compounds where the stereogenic center can reside at sites other than phosphorus. P-chirality exploits the high barrier for inversion of phosphines, which ensures that enantiomers of PRR'R" do not racemize readily. The inversion barrier is relatively insensitive to substituents for triorganophosphines. By contrast, most amine
In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent ...
s of the type NRR′R″ undergo rapid pyramidal inversion.
Research themes
Most chiral phosphines are C2-symmetric diphosphines. Famous examples areDIPAMP
DIPAMP is an organophosphorus compound that is used as a ligand in homogeneous catalysis. It is a white solid that dissolves in organic solvents. Work on this compound by W. S. Knowles was recognized with the Nobel Prize in Chemistry. DIPAMP wa ...
and BINAP. These chelating ligands support catalysts used in asymmetric hydrogenation and related reactions. DIPAMP is prepared by coupling the ''P''-chiral methylphenylanisylphosphine.
''P''-Chiral phosphines are of particular interest in asymmetric catalysis. ''P''-Chiral phosphines have been investigated for two main applications, as ligand
In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's elect ...
s for asymmetric homogeneous catalysts and as nucleophiles in organocatalysis
In organic chemistry, organocatalysis is a form of catalysis in which the rate of a chemical reaction is increased by an organic catalyst. This "organocatalyst" consists of carbon, hydrogen, sulfur and other nonmetal elements found in organic co ...
.
References