The titanium tetrachloride catalyzed condensation of the title acetals with aldehydes, leads to threo or erythro β-hydroxyacids with good stereoselectivity which depends mainly on the nature of the acetal counterion.
Chiral propionate enolate equivalents for the stereoselective synthesis of threo- or erytho-α,-methyl-β-hydroxy acids
作者:Stephen G. Davies、Isabelle M. Dordor-Hedgecock、Peter Warner
DOI:10.1016/s0040-4039(00)94797-x
日期:——
derived from (η5-C5H5)Fe(CO)(PPh3)COCH2CH3 are chiral propionate enolate equivalents which on reaction with aldehydes (RCHO, RMe.Et,iPr,tBu) provide stereoselective syntheses of threo- and erytho-α-methyl-β-hydroxy acids respectively.
Aldol reactions of α-(N,N-dibenzylamino) ethyl ketones
作者:Jane Betty Goh、Bharat R. Lagu、Julie Wurster、Dennis C. Liotta
DOI:10.1016/0040-4039(94)88066-2
日期:1994.8
Aldol reactions of the sodium enolates of α-(N,N-dibenzylamino) ethyl ketones proceed in a highly diastereoselective fashion and result in the formation of the all syn adduct. The observed stereoselectivities are most easily understood in the context of an open transition state.
Asymmetric Aldol Reactions Using (<i>S</i>,<i>S</i>)-(<i>+</i>)-Pseudoephedrine-Based Amides: Stereoselective Synthesis of α-Methyl-β-hydroxy Acids, Esters, Ketones, and 1,3-Syn and 1,3-Anti Diols
作者:Jose L. Vicario、Dolores Badía、Esther Domínguez、Mónica Rodríguez、Luisa Carrillo
DOI:10.1021/jo000035h
日期:2000.6.1
reactions is reported. The reaction of (S, S)-(+)-pseudoephedrine-derived propionamide enolates with several aldehydes yielded exclusively one of the four possible diastereomers in good yields, although transmetalation of the firstly generated lithium enolate with a zirconium(II) salt, prior to the addition of the aldehyde, is necessary in order to achieve high syn selectivity. The so-formed syn-alpha-methyl-beta-hydroxy
Asymmetric synthesis catalyzed by chiral ferrocenylphosphine-transition metal complexes. 3. Preparation of optically active allylsilanes by palladium-catalyzed asymmetric Grignard cross-coupling