Chiraphos is a chiral diphosphine employed as a ligand in organometallic chemistry.

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.