Organic Letters 2004-02-05

Diastereoselective additions of chiral vinylzinc reagents to alpha-chiral aldehydes.

James A Marshall, Patrick Eidam

Index: Org. Lett. 6(3) , 445-8, (2004)

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Abstract

[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.