Diastereoselectivity in the preparation of β-silylesters from αβ-unsaturated esters and amides attached to chiral auxiliaries
作者:Ian Fleming、Nicholas D. Kindon
DOI:10.1039/c39870001177
日期:——
phenyldimethylsilyl-cuprate reagent to cinnamate and crotonate esters and amides of various known chiral auxilaries is diastereoselective, making available β-silylesters of high enantiomeric excess; the sense of the diastereoselectivity is anomalously different from established precedent in the case of silyl-cuprate addition to the cinnamate ester (1, R = Ph, R*=d).
Addition diastéréosélective d'organocuprates à une oxazolidine chirale α,β insaturée: Effet de solvant et application des résultats de la RMN 1H à la détermination de la configuration absolue et de la pureté optique d'aryl-3 alkanals
作者:J. Berlan、Y. Besace、D. Prat、G. Pourcelot
DOI:10.1016/0022-328x(84)85084-6
日期:1984.3
oxazolidine (1) in ether or in hexane leads to 3-phenylbutanals having the S or R configuration, respectively, with high optical yield in the latter case (e.e. ⋍ 80%). The 1H NMR study of the intermediate oxazolidine allows accurate determination of the optical yield and could be applied to the determination of the absolute configuration and optical purity of other 3-arylalkanals.
在乙醚或己烷中,向手性恶唑烷(1)中添加二甲基铜碳酸锂可分别得到具有S或R构型的3-苯基丁醛,在后一种情况下,其光学收率高(ee⋍80%)。中间体恶唑烷的1 H NMR研究可准确测定光学收率,并可用于确定其他3-芳基烷烃的绝对构型和光学纯度。
Stereoselective addition of organoccuprates to a chiral α-β ethylenic oxazolidine: mechanism, nature and reactivity of the intermediates
作者:J. Berlan、Y. Besace、G. Pourcelot、P. Cresson
DOI:10.1016/s0022-328x(00)99310-0
日期:1983.11
reaction of organocuprates with the oxazolidine derived from (E)-cinnamaldehyde and (−)-ephederine gives initially two organocopper intermediates. The steric course of the reaction and spectroscopic data clearly indicate a slow equilibrium between these two highly stable, low reactivity, intermediates. Although an S′N2 mechanism cannot be totally excluded, an unusual 1,2-addition of the organocuprate to the