Chiraphos

Chiraphos
Other names (2S,3S)-(–)-Bis(diphenylphosphino)butane (2R,3R)-(+)-Bis(diphenylphosphino)butane (for the corresponding enantiomer)
Identifiers
CAS number	74839-84-2 (R,R-Enantiomer) Y, 64896-28-2 (S, S-Enantiomer)
PubChem	10113249
ChemSpider	8288775 Y
Jmol-3D images	Image 1
SMILES P(c1ccccc1)(c2ccccc2)[C@H]([C@@H](P(c3ccccc3)c4ccccc4)C)C
InChI InChI=1S/C28H28P2/c1-23(29(25-15-7-3-8-16-25)26-17-9-4-10-18-26)24(2)30(27-19-11-5-12-20-27)28-21-13-6-14-22-28/h3-24H,1-2H3/t23-,24-/m0/s1 Y Key: FWXAUDSWDBGCMN-ZEQRLZLVSA-N Y InChI=1/C28H28P2/c1-23(29(25-15-7-3-8-16-25)26-17-9-4-10-18-26)24(2)30(27-19-11-5-12-20-27)28-21-13-6-14-22-28/h3-24H,1-2H3/t23-,24-/m0/s1 Key: FWXAUDSWDBGCMN-ZEQRLZLVBA
Properties
Molecular formula	C28H28P2
Molar mass	426.47 g/mol
Appearance	White powder
Melting point	104–109 °C
Hazards
EU classification	Irritant (XI)
R-phrases	R36/37/38
S-phrases	S26 S37/39
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Chiraphos is a chiral diphosphine employed as a ligand in organometallic chemistry. This bidentate ligand chelates metals via the two phosphine groups. Its name is derived from its description — being both chiral and a phosphine. Chiraphos is available in two enantiomeric forms, S,S and R,R, each with C₂ symmetry.

Preparation

Chiraphos is prepared from S,S or R,R-2,3-butanediol, which are derived from commercially available S,S or R,R-tartaric acid; the technique of using cheaply available enantiopure starting materials is known as chiral pool synthesis. The diol is tosylated and then the ditosylate is treated with lithium diphenylphosphide.^[1] The ligand was an important demonstration of how the conformation of the chelate ring can affect asymmetric induction by a metal catalyst. Prior to this work, in most chiral phosphines, e.g., DIPAMP, phosphorus was the stereogenic center.

References

1. ^ M. D. Fryzuk, B. Bosnich (1977). "Asymmetric synthesis. Production of optically active amino acids by catalytic hydrogenation". J. Am. Chem. Soc. 99 (19): 6262–6267. doi:10.1021/ja00461a014. PMID 893889. 

This article incorporates information from the revision as of 12:39, 21 June 2008 (UTC) of the equivalent article on the German Wikipedia.