BINAP

BINAP
IUPAC name 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl
Other names BINAP
Identifiers
CAS number	76189-55-4 Y, (R) 76189-56-5 (S)
Properties
Molecular formula	C44H32P2
Molar mass	622.67 g/mol
Appearance	colorless solid
Melting point	239-241 °C (R) 238-240 °C (S)
Solubility in water	organic solvents
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Ball and stick model of BINAP viewed as above

BINAP is an abbreviation for the organophosphorus compound 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl. 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 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˚.

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]

This synthetic method was industrialized by Takasago International Corporation. In part for this work, Ryōji Noyori was awarded the 2001 Nobel Prize in Chemistry.

BINAP is prepared from BINOL^[4][5] (1,1'-bi-2-naphthol) 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 reacted with chlorodiphenylphosphine to make phosphinous acid, diphenyl-[1,1'-binaphthalene]-2-2'-diyl ester (BINAPO).^[6]

References

1. ^ Kitamura, Masato; M. Tokunaga, T. Ohkuma, and R. Noyori (1998). "Asymmetric hydrogenation of 3-oxo carboxylates using BINAP-ruthenium complexes". Org. Syn. 9: 589. http://www.orgsynth.org/orgsyn/prep.asp?prep=cv9p0589. 
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; and Tsuruta, Haruki (1997). "Industrial asymmetric synthesis by use of metal-BINAP catalysts". Nippon Kagaku Kaishi 12: 835−846. 
4. ^ "BINAP: An industrial approach to manufacture". Rhodia (company). http://www.rhodia-phosphines.com/docs/Rhodia.pdf. Retrieved 2008-10-20. 
5. ^ Cai, Dongwei; J. F. Payack, D. R. Bender, D. L. Hughes, T. R. Verhoeven, and P. J. Reider (2004). "(R)-(+)- and (S)-(−)-2,2'-bis(diphenylphosphino)-1,1'-binapthyl (BINAP)". Org. Syn. 10: 112. http://www.orgsynth.org/orgsyn/prep.asp?prep=v76p0006. 
6. ^ 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.