The reaction of B-alkyl-9-borabicyclo[3.3.1]nonanes with aldehydes and ketones. A facile elimination of the alkyl group by aldehydes

M. Mark Midland, Alfonso Tramontano, Stephen A. Zderic

Research output: Contribution to journalArticle

43 Citations (Scopus)

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 languageEnglish (US)
Pages (from-to)203-211
Number of pages9
JournalJournal of Organometallic Chemistry
Volume156
Issue number1
DOIs
StatePublished - Aug 15 1978

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nonanes
Ketones
Aldehydes
aldehydes
ketones
Olefins
Boron
Conformations
elimination
Alcohols
Substitution reactions
Hydrogen
Kinetics
Electrons
alkenes
Benzyl Alcohol
boron
alcohols
Alkenes
substitutes

ASJC Scopus subject areas

  • Biochemistry
  • Chemical Engineering (miscellaneous)
  • Inorganic Chemistry
  • Organic Chemistry
  • Physical and Theoretical Chemistry
  • Materials Science (miscellaneous)
  • Materials Chemistry

Cite this

The reaction of B-alkyl-9-borabicyclo[3.3.1]nonanes with aldehydes and ketones. A facile elimination of the alkyl group by aldehydes. / Midland, M. Mark; Tramontano, Alfonso; Zderic, Stephen A.

In: Journal of Organometallic Chemistry, Vol. 156, No. 1, 15.08.1978, p. 203-211.

Research output: Contribution to journalArticle

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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.",
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N2 - 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.

AB - 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.

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