Abstract
Certain B-alkyl-9-borabicyclo[3.3.1]nonanes (9-BBN) reduce benzaldehyde to benzyl alcohol under exceptionally mild conditions. Factors which contribute to a high rate of reaction include: an increase in the degree of substitution at the position β to the boron (isobutyl > 1-butyl >> ethyl), the ability of the alkyl group to form a syn-planar B-C-C-H conformation (cyclopentyl {reversed tilde equals} norbornyl > sec-butyl >> cyclohexyl), and the presence of an electron-withdrawing para-substituent on the benzaldehyde (p-Cl > p-H > p-CH3O). The B-alkyl group is transformed into an olefin as the benzaldehyde is reduced. Elimination takes place predominantly if not exclusively towards the more highly substituted β hydrogen. The reaction obeys second order kinetics. The observations are consistent with a cyclic mechanism rather than a dehydroboration-reduction pathway.
Original language | English (US) |
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Pages (from-to) | 203-211 |
Number of pages | 9 |
Journal | Journal of Organometallic Chemistry |
Volume | 156 |
Issue number | 1 |
DOIs | |
State | Published - Aug 15 1978 |
ASJC Scopus subject areas
- Biochemistry
- Chemical Engineering (miscellaneous)
- Inorganic Chemistry
- Organic Chemistry
- Physical and Theoretical Chemistry
- Materials Science (miscellaneous)
- Materials Chemistry