Highly Enantioselective Syntheses of anti Homoaldol Products by (−)-Sparteine-Mediated Lithiation/Transmetalation/Substitution of N-Boc Allylic Amines
摘要:
[GRAPHICS](-)-Sparteine-mediated lithiation/transmetalation/substitution of N-Boc allylic amines provides anti-configured homoaldol precursors in yields of 38-85% and enantiomeric ratios of 83:17-99:1. Subsequent O-protection and hydrolysis allows access to O-protected homoaldol adducts in good yields. The absolute configurations of the homoaldol products have been assigned by calculation of optical rotations and by X-ray crystallography of derivatives. A stereochemical course of reaction for the lithiation/transmetalation/substitution sequence is proposed.
Synthetic Applications of Lithiated <i>N</i>-Boc Allylic Amines as Asymmetric Homoenolate Equivalents
作者:Marna C. Whisler、Peter Beak
DOI:10.1021/jo0260084
日期:2003.2.1
transmetalation of the lithiated intermediates and reactions with aldehyde electrophiles can be controlled to afford highly enantioenriched anti homoaldol products. Use of an anti aldehyde homoaldol product as the chiral electrophile in an iterative reaction provides a double homoaldol product containing four stereogenic centers with high diastereoselectivity and enantioselectivity. Reactionpathways are proposed
Highly Enantioselective Syntheses of <i>anti</i> Homoaldol Products by (−)-Sparteine-Mediated Lithiation/Transmetalation/Substitution of <i>N</i>-Boc Allylic Amines
作者:Marna C. Whisler、Louis Vaillancourt、Peter Beak
DOI:10.1021/ol006186o
日期:2000.8.1
[GRAPHICS](-)-Sparteine-mediated lithiation/transmetalation/substitution of N-Boc allylic amines provides anti-configured homoaldol precursors in yields of 38-85% and enantiomeric ratios of 83:17-99:1. Subsequent O-protection and hydrolysis allows access to O-protected homoaldol adducts in good yields. The absolute configurations of the homoaldol products have been assigned by calculation of optical rotations and by X-ray crystallography of derivatives. A stereochemical course of reaction for the lithiation/transmetalation/substitution sequence is proposed.