SuperQuat N-acyl-5,5-dimethyloxazolidin-2-ones for the asymmetric synthesis of alpha-alkyl and beta-alkyl aldehydes.

Bull, S; Davies, S; Nicholson, R; Sanganee, H; Smith, A

Journal article

SuperQuat N-acyl-5,5-dimethyloxazolidin-2-ones for the asymmetric synthesis of alpha-alkyl and beta-alkyl aldehydes.

Abstract:: The proclivity of alpha-branched N-2'-benzyl-3'-phenylpropionyl derivatives of (S)-4-benzyl-5,5-dimethyl-, (S)-4-phenyl-5,5-dimethyl-, (S)-4-isopropyl-5,5-dimethyl-, (S)-4-benzyl- and (S)-4-benzyl-5,5-diphenyl-oxazolidin-2-ones to generate directly 2-benzyl-3-phenylpropionaldehyde upon hydride reduction with DIBAL is investigated. The (S)-4-benzyl-5,5-dimethyl-derivative proved optimal for inhibition of endocyclic nucleophilic attack, giving 2-benzyl-3-phenylpropionaldehyde in good yield upon reduction. Application of this methodology for the asymmetric synthesis of chiral aldehydes via diastereoselective enolate alkylation of a range of (S)-N-acyl-4-benzyl-5,5-dimethyloxazolidin-2-ones to afford and array of alpha-substituted-N-acyl-5,5-dimethyloxazolidin- 2-ones (85-94% de) and subsequent reduction with DIBAL afforded directly non-racemic alpha-substituted aldehydes without loss of stereochemical integrity (87-94% ee). The extension of this protocol for the asymmetric synthesis of beta-substituted aldehydes is demonstrated, via the diastereoselective conjugate addition of a range of organocuprates to (S)-N-acyl-4-phenyl-5,5-dimethyloxazolidin-2-ones which proceeds with high diastereoselectivity (generally > 95% de). Reduction of the conjugate addition products with DIBAL gives non-racemic beta-substituted aldehydes in high yields and in high ee (generally > 95% ee). This methodology is exemplified by the asymmetric synthesis of (R)-3-isopropenylhept-6-enal, which has previously been used in the synthesis of (3Z,6R)-3-methyl-6-isopropenyl-3,9-decadien-1-yl acetate, a component of the sex pheromones of the California red scale.

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APA Style

Bull, S., Davies, S., Nicholson, R., Sanganee, H., & Smith, A. (2003). SuperQuat N-acyl-5,5-dimethyloxazolidin-2-ones for the asymmetric synthesis of alpha-alkyl and beta-alkyl aldehydes. Organic and Biomolecular Chemistry, 1(16), 2886–2899.

MLA Style

Bull, S, et al. “SuperQuat N-Acyl-5,5-Dimethyloxazolidin-2-Ones for the Asymmetric Synthesis of Alpha-Alkyl and Beta-Alkyl Aldehydes.” Organic and Biomolecular Chemistry, vol. 1, no. 16, 2003, pp. 2886–99.

Chicago Style

Bull, S, S Davies, R Nicholson, H Sanganee, and A Smith. 2003. “SuperQuat N-Acyl-5,5-Dimethyloxazolidin-2-Ones for the Asymmetric Synthesis of Alpha-Alkyl and Beta-Alkyl Aldehydes.” Organic and Biomolecular Chemistry 1 (16): 2886–99.
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