60656-55-5Relevant academic research and scientific papers
An 'easy-on, easy-off' protecting group for the enzymatic resolution of (±)-1-phenylethylamine in an aqueous medium
Guranda, Dorel T.,Khimiuk, Andrey I.,Van Langen, Luuk M.,Van Rantwijk, Fred,Sheldon, Roger A.,Svedas, Vytas K.
, p. 2901 - 2906 (2007/10/03)
A new approach has been developed for the biocatalytic resolution of (±)-1-phenylethylamine in 100% aqueous medium based on two integrated enzymatic steps: protection and deprotection of the reactive amine enantiomer catalyzed by the same enzyme-penicillin acylase from Alcaligenes faecalis. An 'easy-on, easy-off' protecting group has been introduced using (R)-phenylglycine amide as the acyl donor. (R)-Phenylglycyl-substituted (R)-1-phenylethylamine was poorly soluble and precipitated at enzymatic acylation in an alkaline medium (pH 10-11), driving the synthesis towards high yields. Conversely at pH 7.5, its solubility was continuously increasing, which rendered the subsequent deacylation by the same enzyme highly efficient. In contrast to the resolutions, which employ one biocatalytic step, the new approach made it possible to exploit two sequential enantioselective enzymatic reactions implementing a double enantioselectivity control. Effective enzymatic resolution of (±)-1-phenylethylamine in an aqueous medium was performed with (R)-phenylglycine amide as an acyl donor using the suggested approach.
Asymmetric Hydrogenation Catalyzed by the (Achiral Base)bis(dimethylglyoximato)cobalt(II)-Chiral Cocatalyst System. The Preparation of a New Type of Chiral Cocatalyst and Its Application to the Asymmetric Hydrogenation of Methyl N-(Acetylamino)acrylate and Benzil
Takeuchi, Seiji,Ohgo,Yoshiaki
, p. 2136 - 2141 (2007/10/02)
As a new type of chiral cocatalyst in the achiral base-coordinated bis(dimethylglyoximato)cobalt(II)-chiral cocatalyst system, tertiary amines with an amide group at α- or β-carbon were prepared, and asymmetric hydrogenation was examined by using them.The optical yield reached 34.5percent enantiomeric excess(ee) by using N--(R)-α-methylbenzylamine; this is the highest value attained so far in the asymmetric hydrogenation of methyl N-(acetylamino)acrylate with this system.The enantioselectivity in the hydrogenation of methyl N-(acetylamino)acrylate was reversed with a configurational alteration of the α-methylbenzylamine moiety of N--α-methylbenzylamine, while it was not reversed in the hydrogenation of benzil by the configurational alteration.From these facts, it is deduced that the hydrogen bond between amide groups of the chiral amino carboxamides and methyl N-(acetylamino)acrylate may act as an attractive force to enhance the enantioselectivity of the asymmetric hydrogenation.
