Iron-Catalyzed, Highly Regioselective Synthesis of α-Aryl Carboxylic Acids from Styrene Derivatives and CO<sub>2</sub>
作者:Mark D. Greenhalgh、Stephen P. Thomas
DOI:10.1021/ja3045053
日期:2012.7.25
The iron-catalyzed hydrocarboxylation of aryl alkenes has been developed using a highly active bench-stable iron(II) precatalyst to give alpha-aryl carboxylic acids in excellent yields and with near-perfect regioselectivity. Using just 1 mol % FeCl2, bis(imino)pyridine 6 (1 mol %), CO2 (atmospheric pressure), and a hydride source (EtMgBr, 1.2 equiv), a range of sterically and electronically differentiated aryl alkenes were transformed to the corresponding alpha-aryl carboxylic acids (up to 96% isolated yield). The catalyst was found to be equally active with a loading of 0.1 mol %. Preliminary mechanistic investigations show that an iron-catalyzed hydrometalation is followed by transmetalation and reaction with the electrophile (CO2).
Microbial Deracemization of α-Substituted Carboxylic Acids
作者:Dai-ichiro Kato、Satoshi Mitsuda、Hiromichi Ohta
DOI:10.1021/ol0170556
日期:2002.2.1
[GRAPHICS]n enzyme system of Nocardia diaphanozonaria JCM 3208 catalyzes the inversion of the chirality of various alpha-substituted carboxylic acids, such as 2-phenylpropanoic acid and 2-phenoxypropanoic acid derivatives, via a novel deracemization reaction.
Microbial Deracemization of α-Substituted Carboxylic Acids: Substrate Specificity and Mechanistic Investigation
作者:Dai-ichiro Kato、Satoshi Mitsuda、Hiromichi Ohta
DOI:10.1021/jo034253x
日期:2003.9.1
A new enzymatic method for the preparation of opticallyactive alpha-substituted carboxylic acids is reported. This technique is called deracemization reaction, which provides us with a route to obtain the enantiomerically pure compounds, theoretically in 100% yield starting from the racemic mixture. This means that the synthesis of a racemate is almost equal to the synthesis of the optically active