320606-29-9

Upstream product

• 14371-10-9 (E)-3-phenylpropenal 
• 811-49-4 ethyllithium 
• 1177266-27-1 (2R,1'S)-N-tert-butoxy-N-1'-(1''-naphthyl)ethyl 2-benzylbutanamide 
• 100-39-0 benzyl bromide 

Relevant academic research and scientific papers

The chiral auxiliary N-1-(1′-Naphthyl)ethyl-O-tert- butylhydroxylamine: A chiral weinreb amide equivalent

The chiral auxiliary N-1-(1′-naphthyl)ethyl-O-terf- butylhydroxylamine is readily prepared from N-hydroxyphthalimide in four steps, with resolution giving access to both enantiomers in >98% ee, on a multigram (>25 g) scale. Conversion to a range of N-acyl derivatives, followed by highly diastereoselective alkylation (≥94% de) gives the corresponding chiral, 2-substituted derivatives as single diastereoisomers (>98% de) after chromatography. Reductive cleavage with LiAlH4 allows direct access to chiral aldehydes, and treatment with MeLi gives chiral methyl ketones in excellent enantiopurity (≥94% ee). The auxiliary can be recovered in >98% ee and recycled.

SuperQuat N-acyl-5,5-dimethyloxazolidin-2-ones for the asymmetric synthesis of α-alkyl and β-alkyl aldehydes

The proclivity of α-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 an array of α-substituted-N-acyl-5,5-dimethyloxazolidin-2-ones (85-94% de) and subsequent reduction with DIBAL afforded directly non-racemic α-substituted aldehydes without loss of stereochemical integrity (87-94% ee). The extension of this protocol for the asymmetric synthesis of β-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 β-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.

An easy access to enantio-enriched α-substituted aldehydes by carbolithiation of β-phenyl or β-silyl-α,β-ethylenic aldehydes, protected with the monolithioamide of a chiral diamine

Lithium amide derived from N,N,N′-trimethyl-1,2-diphenylethanediamine converts cinnamaldehyde to a lithium alkoxyamide which undergoes a regio- and stereoselective carbolithiation upon addition of various organolithiums. Subsequent hydrolysis or trapping with MeI delivers α-mono-, or α,β-disubstituted 3-phenylpropanals with e.e.s of 76-96%. Extension to a silylated α-enal is possible.

SuperQuat, (S)-4-benzyl-5,5-dimethyl-oxazolidin-2-one for the asymmetric synthesis of α-substituted-aldehydes

Reduction of α-substituted-(S)-N-acyl-4-benzyl-5,5-dimethyl-oxazolidin-2-ones with DIBAL-H in CH2Cl2 affords α-substituted aldehydes with no loss of stereochemical integrity at their α-centre. Copyright (C) 2000 Elsevier Science Ltd.