Diastereoselective additions of chiral vinylzinc reagents to alpha-chiral aldehydes.
[reaction: see text] Additions of vinylic zinc bromide reagents to alpha-chiral aldehydes (R(1) = CH(2)OTBS, R(2) = Me; R(1) = Me, R(2) = OTBS) in the presence of lithiated (+)- or (-)-N-methylephedrine proceed with predominant reagent control to afford anti or syn adducts stereoselectively, except when the aldehydes possess an alkoxy substituent at the alpha- or beta-positions (R(1) = Me, R(2) = OBn; R(1) = CH(2)OBn, R(2) = Me), in which case chelation-controlled adducts predominate.
Marshall
James A
JA
Department of Chemistry, University of Virginia, PO Box 400319, Charlottesville, Virginia 22904, USA. jam5x@virginia.edu
Eidam
Patrick
P
D000447:Aldehydes / Q000737:chemistry*; D004809:Ephedrine / Q000031:analogs & derivatives / Q000737:chemistry; D008094:Lithium / Q000737:chemistry; D008274:Magnesium / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism; D014753:Vinyl Compounds / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*
D000447:Aldehydes; D014753:Vinyl Compounds; C041707:N-methylephedrine; C003763:vinyl bromide; D008094:Lithium; D004809:Ephedrine; D008274:Magnesium; D015032:Zinc