Water-Accelerated Aldol Reaction of Ketene Silyl Acetals with Carbonyl Compounds
作者:Teck-Peng Loh、Li-Chun Feng、Lin-Li Wei
DOI:10.1016/s0040-4020(00)00630-x
日期:2000.9
The aldol reactions of ketene silyl acetals with reactive aldehydes proceed smoothly in water to afford the corresponding aldol products in good yields.
乙烯酮甲硅烷基缩醛与反应性醛的醛醇缩合反应在水中可顺利进行,从而以高收率得到相应的醛醇缩合产物。
Highly Stereoselective Aldol Reaction of Chiral 3-(<i>p</i>-Tolylsulfinyl)furfural with Silyl Ketene Acetal Catalyzed by Lanthanide Triflate
作者:Yoshitsugu Arai、Tsutomu Masuda、Yukio Masaki
DOI:10.1055/s-1997-1068
日期:——
The aldol reaction of optically active 3-(p-tolylsulfinyl)furfural with silyl ketene acetal catalyzed by a lanthanide triflate proceeded smoothly to give the syn- and anti-aldol products with high diastereoselectivities in high yield.
Microbiological asymmetric reduction of methyl 3-(2-furyl)-2-methyl-3-oxopropionate (5) by various yeasts was carried out. Four kinds of methyl 3-(2-furyl)-3-hydroxy-2-methyl propionates (6a-6d) could be obtained separately from the prochiral β-keto ester 5 by reduction with properly selected microorganisms. In particular, the desired syn-isomer 6a was obtained with high optical purity (>99% e.e.). Both the chemical yield and the optical purity of the reduction products (6a-6d) were significantly improved when fermentation was carried out on a large scale using a 30 1 jar fermentor or a 200 1 tank.
The first example of the Wittig rearrangement of furfuryl ethers is presented and its application to the preparation of 3-(2-furyl)-3-hydroxy-2-methylpropionates is described.
Generation of (<i>E</i>)-Silylketene Acetals in a Rhodium-DuPhos Catalyzed Two-Step Reductive Aldol Reaction
作者:Cun-Xiang Zhao、Jonathan Bass、James P. Morken
DOI:10.1021/ol016279l
日期:2001.9.1
[GRAPHICS]Mechanistic studies employing in situ NMR analysis implicate intermediate silicon enolates as reactive intermediates in the Rh-DuPhos catalyzed two-step reductive aldol reaction with Cl2MeSiH. These enolates undergo noncatalyzed reaction with a variety of aldehydes to give the derived syn-aldol adduct in high yields and diastereoselection.