DIOP
{{Chembox
| ImageFile = (S,S)-DIOP.svg
| ImageSize =
| ImageAlt =
| IUPACName = O-Isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane
| PIN = {[(4R,5R)-2,2-Dimethyl-1,3-dioxolane-4,5-diyl]bis(methylene)}bis(diphenylphosphane)
| OtherNames = (−)-2,3-O-Isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane
(−)-1,4-Bis(diphenylphosphino)-1,4-dideoxy-2,3-O-isopropylidene-L-threitol
(+)-2,3-O-Isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane
(+)-1,4-Bis(diphenylphosphino)-1,4-dideoxy-2,3-O-isopropylidene-L-threitol
|Section1={{Chembox Identifiers
| CASNo =32305-98-9
| CASNo_Comment = (–)
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo1 =37002-48-5
| CASNo1_Comment = (+)
| CASNo1_Ref = {{fdacite|correct|FDA}}
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = ESK57W53CI
| UNII_Comment = (–)
| UNII1 = 5P52K0IJ7T
| UNII1_Ref = {{fdacite|correct|FDA}}
| UNII1_Comment = (+)
| PubChem =
| PubChem1 = 395120
| PubChem1_Comment = (–)
| ChemSpiderID1 = 350240
| ChemSpiderID1_Comment = (–)
| SMILES = CC1(O[C@H]([C@@H](O1)CP(c2ccccc2)c3ccccc3)CP(c4ccccc4)c5ccccc5)C
| SMILES_Comment = (–)
| InChI = 1S/C31H32O2P2/c1-31(2)32-29(23-34(25-15-7-3-8-16-25)26-17-9-4-10-18-26)30(33-31)24-35(27-19-11-5-12-20-27)28-21-13-6-14-22-28/h3-22,29-30H,23-24H2,1-2H3/t29-,30-/m0/s1
| InChI_Comment = (–)
| InChIKey = VCHDBLPQYJAQSQ-KYJUHHDHSA-N
}}
|Section2={{Chembox Properties
| C=31 | H=32 | O=2 | P=2
| Appearance = White solid
| Density =
| MeltingPtC = 86 to 89
| BoilingPt =
| Solubility = Insoluble}}
|Section3={{Chembox Hazards
| MainHazards =
| FlashPt =
| AutoignitionPt = }}
}}
DIOP (2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane) is an organophosphorus compound that is used as a chiral ligand in asymmetric catalysis. It is a white solid that is soluble in organic solvents.
DIOP is prepared from the acetonide of d,l-tartaric acid, which is reduced prior to attachment of the PPh2 substituents.
Use
The DIOP ligand binds to metals via conformationally flexible seven-membered C4P2M chelate ring.
DIOP is a historically important in the development of ligands for use in asymmetric catalysis, an atom-economical method for the preparation of chiral compounds. Described in 1971, it was the first example of a C2-symmetric diphosphine.{{cite journal | doi = 10.1039/C29710000481 | title = The asymmetric synthesis of hydratropic acid and amino-acids by homogeneous catalytic hydrogenation | year = 1971 | last1 = Dang | first1 = T. P. | last2 = Kagan | first2 = H. B. | journal = Journal of the Chemical Society D: Chemical Communications | issue = 10 | pages = 481}} Its complexes have been applied to the reduction of prochiral olefins, ketones, and imines. Knowles et al. independently reported the related C2-symmetric diphosphine DIPAMP.{{cite book |author1=Shang, G. |author2=Li, W. |author3=Zhang, X. | chapter = Transition Metal-Catalyzed Homogeneous Asymmetric Hydrogenation | title = Catalytic Asymmetric Synthesis | edition = 3rd | editor = Iwao Ojima | publisher = John Wiley & Sons | location = New York | year = 2010 | pages = 343–436}}
Since the discovery of DIOP, many analogues of DIOP have been introduced. These DIOP derivatives include MOD-DIOP, Cy-DIOP, DIPAMP, and DBP-DIOP. Out of many derivatives, DBP-DIOP exhibits good regio- and enantioselectivity in the hydroformylation of butenes and styrene. DIOP was the first chiral ligand used in the platinum-tin-catalyzed hydroformylation. The reactivity, chemo – and the enantioselectivity of DIOP is influenced by CO and H2 pressure and polarity of the solvents. The best results in asymmetric hydroformylation are achieved in solvents with medium polarity: benzene and toluene.{{cite journal |author1=Agbossou, F. |author2=Carpentier, J. |author3=Mortreux, A. | title = Asymmetric Hydroformylation | journal = Chem. Rev. | year = 1995 | volume = 95 | pages = 2485–2806 | doi = 10.1021/cr00039a008 | issue = 7}}