A new family of ferrocenylphosphane ligands has been prepared. Their flexible synthesis allows many structural modifications. The asymmetric induction of these ligands was examined in the hydrogenation of functionalized C=C, C=O, and C=N bonds. The enantioselectivity of the reaction was strongly dependent on the substituent R at the position alpha to the ferrocene moiety. In many cases, both enantiomeric
A process for preparing esters and organic halides, which comprises reacting
- a salt having a melting point of less than 100°C (at 1 bar) and of the formula
(K+)n X (COO-)n,
in which
K+ is an organic cation,
X (COO-)n is an organic anion having an n-valent organic group X which is substituted by n carboxylate groups COO-, and
n is 1, 2 or 3,
- with an organic halogen compound (Hal)mY,
in which
Hal is a halogen atom,
Y is an m-valent organic group, and
m is 1, 2 or 3,
to give an ester and a halide K+ Hal-.
Highly Enantioselective Acylation of <i>rac</i>-Alkyl Lactates Using <i>Candida antarctica</i> Lipase B
作者:Yeon Soo Lee、Joo Hee Hong、Nan Young Jeon、Keehoon Won、Bum Tae Kim
DOI:10.1021/op0498722
日期:2004.11.1
cases, only alkyl (R)-lactate was stereoselectively acylated at >99.5% ee. The lipase-catalyzed acylation rate of the alkyl lactates was affected by the nature of the organicsolvents, but showed no correlation to log P of the solvent. The lipase-catalyzed acylation rate of the alkyl lactates was enhanced by increasing the chain length of the vinyl alkanoate from acetyl to butanoyl and by raising the
通过在温和条件下使用南极假丝酵母脂肪酶 B,已经完成了来自外消旋混合物的 (R)-乳酸烷基酯与链烷酸乙烯酯的高度对映选择性酰化。本研究考察了有机溶剂、乳酸烷基酯和链烷酸乙烯酯的烷基链长度、反应温度对对映体过量以及反应速率的影响。在所有情况下,只有 (R)-乳酸烷基酯在 >99.5% ee 时被立体选择性酰化。乳酸烷基酯的脂肪酶催化酰化速率受有机溶剂性质的影响,但与溶剂的 log P 无关。通过增加链烷酸乙烯酯从乙酰基到丁酰基的链长以及将反应温度提高到 65 °C,可以提高乳酸烷基酯的脂肪酶催化的酰化速率。
Ruthenium tetroxide catalyzed oxidations of aromatic and heteroaromatic rings
作者:Masaji Kasai、Herman Ziffer
DOI:10.1021/jo00162a009
日期:1983.7
Freudenberg; Markert, Chemische Berichte, 1927, vol. 60, p. 2447