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CAS number 32305-98-9 (–), 37002-48-5 (+)
Molecular formula C31H32O2P2
Molar mass 498.53 g mol−1
Appearance White solid
Melting point 86 to 89 °C (187 to 192 °F; 359 to 362 K)
Solubility in water Insoluble
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

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.


The DIOP ligand binds to metals via conformationally flexible seven-membered C5P2M chelate ring.[1][2]

DIOP is a historically important in the development of asymmetric catalysis, an atom-economical method for the preparation of chiral compounds. Described in 1973, it was of the first examples of a C2-symmetric disphosphines,[3] Its complexes have been applied to the reduction of prochiral olefins, ketons, and imines. Knowles et al. independently reported the related C2-symmetric bdiphosphine DIPAMP.[1]

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.[2]


  1. ^ a b Shang, G., Li, W., Zhang, X. (2010). "Transition Metal-Catalyzed Homogeneous Asymmetric Hydrogenation". In Iwao Ojima. Catalytic Asymmetric Synthesis (3rd ed.). New York: John Wiley & Sons. pp. 343–436. 
  2. ^ a b Agbossou, F., Carpentier, J., Mortreux, A. (1995). "Asymmetric Hydroformylation". Chem. Rev. 95 (7): 2485–2806. doi:10.1021/cr00039a008. 
  3. ^ Dang, T. P.; Kagan, H. B. (1971). "The asymmetric synthesis of hydratropic acid and amino-acids by homogeneous catalytic hydrogenation". Journal of the Chemical Society D: Chemical Communications (10): 481. doi:10.1039/C29710000481.