Tetrahedron Asymmetry p. 1803 - 1827 (1993)
Update date:2022-08-31
Topics:
Augustine
Tanielyan
Doyle
The room temperature and atmospheric pressure hydrogenation of ethyl pyruvate over Pt/Al2O3 catalysts modified by varying amounts of dihydrocinchonidine was examined. Data were obtained which showed that the hydrogenation occurred on the corner atoms and adatoms on the Pt crystallites in the catalyst. The formation of (S) ethyl lactate was observed when very low concentrations of the alkaloid modifier were used while at higher modifier concentrations the (R) lactate was produced. The formation of the (R) lactate was accompanied by an increase in the hydrogenation rate. A working hypothesis was formulated to explain these results and to serve as a model for the design of future experiments. This model suggested that the initial adsorption of the dihydrocinchonidine takes place on the face atoms adjacent to the corner atoms on the metal crystallite. This will place the chiral portion of the alkaloid close to the corner atom active site. Enantioselective pyruvate adsorption would be vacilitated by a hydrogen bond between the C9 OH of the alkaloid and the ethoxy oxygen of the pyruvate and hydrogenation of the keto group will lead to (S) lactate formation. In order to place the chiral portion of the modifier near an adatom it is proposed that the alkaloid is adsorbed in an edge-on manner on the face near the adatom active site. In this way the modifier can interact directly with the pyruvate to change its adsorption characteristics. This will lead to an increase in reaction rate and the formation of the (R) lactate.
View Morewebsite:http://www.uvchemkleys.com
Contact:+86 21 3868 0172
Address:RM-1203, Ziguang Building, #341 Shangcheng Road, Pudong Dist, Shanghai
SHANDONG AONA CHEMICAL CO.,LTD.
Contact:86-532-85762926
Address:LIUYUAN TOWN, ZAOZHUANG CITY, SHANGDONG PROVINCE.
Contact:+86-134-5286-9121
Address:Add: Wing Tuck Commercial Centre, 177-183 Wing Lok Street, Hong Kong,
Linyi Shengxin Pharmaceutical R&D Co., Ltd
Contact:+86-18653953873
Address:West First of Yufeng Road, Yishui County
CHANGYI CITY FENGRUN FINE CHEMICAL CO.,LTD
website:http://www.fengrunhuagong.com
Contact:+86-536-7869976
Address:Changyi Coastal Economic Development Zone
Doi:10.1039/c8cc05402a
(2018)Doi:10.1021/j150397a002
(1940)Doi:10.1007/BF00574612
(1986)Doi:10.1039/c4ta04574b
(2015)Doi:10.1016/j.jorganchem.2010.05.019
(2010)Doi:10.1021/jo00212a029
(1985)