Diisopinocampheylborane
2BH.png) |
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IUPAC name
Bis{(1S,2S,3S,5R)-2,6,6-trimethylbicyclo[3.1.1]heptan-3-yl} borane
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| Other names
(+)-Di-3-pinanylborane; Diisopinocampheylborane; Ipc2BH
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| Identifiers | |
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3D model (JSmol)
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| Abbreviations | Ipc2BH |
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| Properties | |
| C20H35B | |
| Molar mass | 286.31 g·mol−1 |
| Appearance | Colorless solid |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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| Infobox references | |
Diisopinocampheylborane is an organoborane that is useful for asymmetric synthesis. This colourless solid is the precursor to a range of related reagents. The compound was reported in 1961 by Zweifel and Brown in a pioneering demonstration of asymmetric synthesis using boranes. The reagent is mainly used for the synthesis of chiral secondary alcohols.
Diisopinocampheylborane was originally prepared by hydroboration of excess α-pinene with borane, but it is now more commonly generated from borane-methyl sulfide (BMS).
The compound can be isolated as a solid. However, because it is quite sensitive to water and air, this reagent is often generated in situ and used as a solution.
Diisopinocampheylborane is monomeric, in contrast to diborane and many of its less bulky analogues.
Oxidation of diisopinocampheylborane with basic hydrogen peroxide gives isopincampheol. Methanolysis gives methoxydiisopinocampheylborane
Because of the large size of the α-pinenyl substituents, diisopinocampheylborane only hydroborates unhindered alkenes. These reactions proceed with high enantioselectivity. 2-Butene, 2-pentene, 3-hexene are converted to the respective chiral alcohols in high ee's.Norbornene under the same conditions gave an 83% ee. Hetrocycles (dihydrofuran, dihydrothiophene, dihydropyrrole, tetrahydropyran) give the alcohols in ≥99% ee; the high ee's reflect their constrained conformations.
It adds to alkynes to form the corresponding vinyldiisopinocampheylboranes
In a highly stereoselective reaction, allyldiisopinocampheylboranes converts aldehydes to the homologated alcohols, rapidly even at -100 °C. The alkyldiisopinocampheylboranes, which result from the addition to alkenes, usefully react with a range of different reagents. Hydroxylamine-O-sulfonic acid provides 3-pinanamine.
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