(R)-2-Methyl-CBS-oxazaborolidine

(R)-2-Methyl-CBS-oxazaborolidine
Names
	IUPAC name (3aR)-1-Methyl-3,3-diphenyltetrahydro-3H-pyrrolo[1,2-c][1,3,2]oxazaborole
	Other names (R)-Methyl oxazaborolidine; (R)-(+)-2-methyl-CBS-oxazaborolidine
Identifiers
CAS Number	112022-83-0 ;
3D model (JSmol)	Interactive image;
ChemSpider	8014210 ;
ECHA InfoCard	100.103.901
EC Number	601-151-0;
PubChem CID	9838490;
CompTox Dashboard (EPA)	DTXSID40920652 ;
	InChI InChI=1S/C18H20BNO/c1-19-20-14-8-13-17(20)18(21-19,15-9-4-2-5-10-15)16-11-6-3-7-12-16/h2-7,9-12,17H,8,13-14H2,1H3/t17-/m1/s1 Key: VCDGSBJCRYTLNU-AZWGFFAPSA-N ; InChI=1/C18H20BNO/c1-19-20-14-8-13-17(20)18(21-19,15-9-4-2-5-10-15)16-11-6-3-7-12-16/h2-7,9-12,17H,8,13-14H2,1H3/t17-/m1/s1 Key: VCDGSBJCRYTLNU-AZWGFFAPBY;
	SMILES O2B(N1CCC[C@@H]1C2(c3ccccc3)c4ccccc4)C;
Properties
Chemical formula	C18H20BNO
Molar mass	277.17 g·mol−1
Appearance	Colorless to pale yellow liquid (in toluene)
Density	0.95 g/mL
Melting point	85 to 95 °C (185 to 203 °F; 358 to 368 K)
Boiling point	111 °C (232 °F; 384 K)
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H224, H225, H302, H304, H315, H318, H319, H332, H335, H336, H361, H373
Precautionary statements	P201, P202, P210, P233, P240, P241, P242, P243, P260, P261, P264, P270, P271, P280, P281, P301+P310, P301+P312, P302+P352, P303+P361+P353, P304+P312, P304+P340, P305+P351+P338, P308+P313, P310, P312, P314, P321, P330, P331, P332+P313, P337+P313, P362, P370+P378, P403+P233, P403+P235, P405, P501
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

(R)-2-Methyl-CBS-oxazaborolidine is an organoboron catalyst that is used in organic synthesis. This catalyst, developed by Itsuno^[1]^[2] and Elias James Corey,^[3]^[4]^[5] is generated by heating (R)-(+)-2-(diphenylhydroxymethyl) pyrrolidine along with trimethylboroxine or methylboronic acid. It is an excellent tool for the synthesis of alcohols in high enantiomeric ratio. Generally, 2-10 mol% of this catalyst is used along with borane-tetrahydrofuran (THF), borane-dimethylsulfide, borane-N,N-diethylaniline, or diborane as the borane source. Enantioselective reduction using chiral oxazaborolidine catalysts has been used in the synthesis of commercial drugs such as ezetimibe and aprepitant.

References

^ Hirao, A.; Itsuno, S.; Nakahama, S.; Yamazaki, N. (1981). "Asymmetric reduction of aromatic ketones with chiral alkoxy-amineborane complexes". J. Chem. Soc. Chem. Commun.: 315–317. doi:10.1039/C39810000315.
^ Itsuno, S.; Nakano,M.; Miyazaki, K.; Masuda, H.; Ito, K.; Hirao, A.; Nakahama, S. (1985). "Asymmetric synthesis using chirally modified borohydrides. Part 3. Enantioselective reduction of ketones and oxime ethers with reagents prepared from borane and chiral amino alcohols". J. Chem. Soc. Perkin Trans. 1: 2039–2044. doi:10.1039/p19850002039.
^ Corey, E. J.; Bakshi, R. K.; Shibata, S. (1987). "Highly enantioselective borane reduction of ketones catalyzed by chiral oxazaborolidines. Mechanism and synthetic implications". J. Am. Chem. Soc. 109 (18): 5551–5553. doi:10.1021/ja00252a056.
^ Corey, E. J.; Bakshi, R. K.; Shibata, S.; Chen, C.-P.; Singh, V. K. (1987). "A stable and easily prepared catalyst for the enantioselective reduction of ketones. Applications to multistep syntheses". J. Am. Chem. Soc. 109 (25): 7925–7926. doi:10.1021/ja00259a075.
^ Corey, E. J.; Azimioara,M.; Sarshar, S. (1992). "X-Ray crystal structure of a chiral oxazaborolidine catalyst for enantioselective carbonyl reduction". Tetrahedron Lett. 33 (24): 3429–3430. doi:10.1016/S0040-4039(00)92654-6.

[1] Hirao, A.; Itsuno, S.; Nakahama, S.; Yamazaki, N. (1981). "Asymmetric reduction of aromatic ketones with chiral alkoxy-amineborane complexes". J. Chem. Soc. Chem. Commun.: 315–317. doi:10.1039/C39810000315.

[2] Itsuno, S.; Nakano,M.; Miyazaki, K.; Masuda, H.; Ito, K.; Hirao, A.; Nakahama, S. (1985). "Asymmetric synthesis using chirally modified borohydrides. Part 3. Enantioselective reduction of ketones and oxime ethers with reagents prepared from borane and chiral amino alcohols". J. Chem. Soc. Perkin Trans. 1: 2039–2044. doi:10.1039/p19850002039.

[3] Corey, E. J.; Bakshi, R. K.; Shibata, S. (1987). "Highly enantioselective borane reduction of ketones catalyzed by chiral oxazaborolidines. Mechanism and synthetic implications". J. Am. Chem. Soc. 109 (18): 5551–5553. doi:10.1021/ja00252a056.

[4] Corey, E. J.; Bakshi, R. K.; Shibata, S.; Chen, C.-P.; Singh, V. K. (1987). "A stable and easily prepared catalyst for the enantioselective reduction of ketones. Applications to multistep syntheses". J. Am. Chem. Soc. 109 (25): 7925–7926. doi:10.1021/ja00259a075.

[5] Corey, E. J.; Azimioara,M.; Sarshar, S. (1992). "X-Ray crystal structure of a chiral oxazaborolidine catalyst for enantioselective carbonyl reduction". Tetrahedron Lett. 33 (24): 3429–3430. doi:10.1016/S0040-4039(00)92654-6.

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See also

References