Stereoselective functionalisation of cis- and trans-2-ferrocenyl-3-pivaloyl-4-alkyl-1,3-oxazolidin-5-ones: asymmetric synthesis of (R)- and (S)-2-alkyl-2-aminopent-4-enoic acids and (2R,3S)-2-amino-2-methyl-3-hydroxy-3-phenylpropanoic acid.
Treatment of a range of cis- and trans-2-ferrocenyl-3-pivaloyl-4-alkyl-1,3-oxazolidin-5-ones with LDA followed by the addition of allyl bromide promotes highly stereoselective allylation (>98% de) at the 4-position of the oxazolidinone ring anti to the stereodirecting 2-ferrocenyl group. Hydrolysis of the resultant 4,4-disubstituted oxazolidinones (>98% de) yields enantiomeric (R)- and (S)-2-alkyl-2-aminopent-4-enoic acids in high ee. Furthermore, the aldol reaction of the lithium enolate of cis-2-ferrocenyl-3-pivaloyl-4-methyl-1,3-oxazolidin-5-one with benzaldehyde followed by in situ O-protection affords O-protected aldol products in >98% de, with hydrolysis affording (2R,3S)-2-amino-2-methyl-3-hydroxy-3-phenylpropanoic acid in >98% de.
Alonso
Francisco
F
Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, UKOX1 3TA.
Davies
Stephen G
SG
Elend
Almut S
AS
Leech
Michael A
MA
Roberts
Paul M
PM
Smith
Andrew D
AD
Thomson
James E
JE
D000501:Allylglycine / Q000138:chemical synthesis* / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D023303:Oxazolidinones / Q000737:chemistry*; D010666:Phenylpropionates / Q000138:chemical synthesis*; D013237:Stereoisomerism; D013379:Substrate Specificity
C538956:(2R,3S)-2-amino-2-methyl-3-hydroxy-3-phenylpropanoic acid; D023303:Oxazolidinones; D010666:Phenylpropionates; D000501:Allylglycine