BINAP

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BINAP
BINAP Enantiomers Structural Formulae V.1.svg
Identifiers
CAS number 76189-55-4 (R) YesY, 76189-56-5 (S) YesY
ChemSpider 551072 (Rac)
Jmol-3D images Image 1
Properties
Molecular formula C44H32P2
Molar mass 622.67 g mol−1
Appearance Colorless solid
Melting point 239-241 °C (R)
238-240 °C (S)
Solubility in water organic solvents
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references
Ball and stick model of BINAP viewed as above

BINAP (2,2'-bis(diphenylphosphino)-1,1'-binaphthyl) is an organophosphorus compound. This chiral ligand is widely used in asymmetric synthesis. It consists of a pair of 2-diphenylphosphinonaphthyl groups linked at the 1 and 1´ positions. This C2-symmetric framework lacks a stereogenic atom, but has axial chirality due to restricted rotation (atropisomerism). The barrier to racemization is high due to steric hindrance, which limits rotation about the bond linking the naphthyl rings. The dihedral angle is approximately 90˚.

Use as ligand in asymmetric catalysis[edit]

BINAP is used in organic synthesis for enantioselective transformations catalyzed by its complexes of ruthenium, rhodium, and palladium.[1] As pioneered by Ryōji Noyori and his co-workers, Rh complexes of BINAP are useful for the synthesis of (–)-menthol.[2][3]

Subsequent studies revealed that related diphosphines with a narrower dihedral angle between the aromatic faces give catalysts that are more enantioselective. One such ligand is SEGPHOS.[4]

Preparation[edit]

BINAP is prepared from BINOL[5][6] via its bis-triflate derivatives. Both the (R)- and (S)-enantiomers, as well as the racemate, are commercially available. One of the wide applications include chemoselective hydrogenation, where BINAP is conjugated to Rh.

BINOL can be treated with chlorodiphenylphosphine to make phosphinous acid, diphenyl-[1,1'-binaphthalene]-2-2'-diyl ester (BINAPO).[7]

References[edit]

  1. ^ Kitamura, Masato; M. Tokunaga; T. Ohkuma; R. Noyori (1998). "Asymmetric hydrogenation of 3-oxo carboxylates using BINAP-ruthenium complexes". Org. Syn. 9: 589. 
  2. ^ Akutagawa, S (1992). "A practical synthesis of (-)-menthol with the Rh-BINAP catalyst". Chirality Ind.: 313−323. 
  3. ^ Kumobayashi, Hidenori; Sayo, Noboru; Akutagawa, Susumu; Sakaguchi, Toshiaki; Tsuruta, Haruki (1997). "Industrial asymmetric synthesis by use of metal-BINAP catalysts". Nippon Kagaku Kaishi 12: 835−846. 
  4. ^ Shimizu, H., Nagasaki, I., Matsumura, K., Sayo, N., Saito, T. (2007). "Developments in Asymmetric Hydrogenation from an Industrial Perspective". Acc. Chem. Res. 40 (12): 1385–1393. doi:10.1021/ar700101x. PMID 17685581. 
  5. ^ "BINAP: An industrial approach to manufacture". Rhodia (company). Retrieved 2008-10-20. 
  6. ^ Cai, Dongwei; J. F. Payack; D. R. Bender; D. L. Hughes; T. R. Verhoeven; P. J. Reider (2004). "(R)-(+)- and (S)-(−)-2,2'-bis(diphenylphosphino)-1,1'-binapthyl (BINAP)". Org. Syn. 10: 112. 
  7. ^ Nakajima, Makoto; S. Kotani; T. Ishizuka; S. Hashimoto (2005). "Chiral Phosphine Oxide BINAPO as a Catalyst for Enantioselective Allylation of Aldehydes with Allyltrichlorosilanes". ChemInform 36 (16). doi:10.1002/chin.200516031.