(R)-2-Methyl-CBS-oxazaborolidine
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| Names | |
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| IUPAC name
(3aR)-1-Methyl-3,3-diphenyltetrahydro-3H-pyrrolo[1,2-c][1,3,2]oxazaborole
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| Other names
(R)-Methyl oxazaborolidine; (R)-(+)-2-methyl-CBS-oxazaborolidine
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| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.103.901 |
CompTox Dashboard (EPA)
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| Properties | |
| 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) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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(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.
See also
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. I: 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.