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Chiraphos
Names
	Preferred IUPAC name rel-[(2R,3R)-Butane-2,3-diyl]bis(diphenylphosphane)
	Other names (2S,3S)-(–)-Bis(diphenylphosphino)butane; (2R,3R)-(+)-Bis(diphenylphosphino)butane;
Identifiers
CAS Number	74839-84-2 (R,R) ; 64896-28-2 (S,S) ;
3D model (JSmol)	Interactive image;
ChemSpider	8288775 ;
ECHA InfoCard	100.152.152
PubChem CID	10113249;
UNII	1T086B9Q1J (R,R) ; 6QR78GZL9B (S,S) ;
CompTox Dashboard (EPA)	DTXSID60435814 ;
	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 Key: FWXAUDSWDBGCMN-ZEQRLZLVSA-N ; 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;
	SMILES P(c1ccccc1)(c2ccccc2)[C@H]([C@@H](P(c3ccccc3)c4ccccc4)C)C;
Properties
Chemical formula	C28H28P2
Molar mass	426.47 g/mol
Appearance	White powder
Melting point	104 to 109 °C (219 to 228 °F; 377 to 382 K)
Hazards
	GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H319, H335
Precautionary statements	P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) 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. As a C₂-symmetric ligand, 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

^ Fryzuk, M. D.; Bosnich, B. (1977). "Asymmetric synthesis. Production of optically active amino acids by catalytic hydrogenation". Journal of the American Chemical Society. 99 (19): 6262–6267. doi:10.1021/ja00461a014. PMID 893889.