Chiraphos

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.

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) Y 64896-28-2 (S,S) Y
3D model (JSmol)	Interactive image
ChemSpider	8288775 Y
ECHA InfoCard	100.152.152
PubChem CID	10113249
UNII	1T086B9Q1J (R,R) Y 6QR78GZL9B (S,S) Y
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 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
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). N verify (what is YN ?) Infobox references

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.