Highly Efficient Synthesis of β-Amino Acid Derivatives via Asymmetric Hydrogenation of Unprotected Enamines
作者:Yi Hsiao、Nelo R. Rivera、Thorsten Rosner、Shane W. Krska、Eugenia Njolito、Fang Wang、Yongkui Sun、Joseph D. Armstrong、Edward J. J. Grabowski、Richard D. Tillyer、Felix Spindler、Christophe Malan
DOI:10.1021/ja047901i
日期:2004.8.1
A direct asymmetrichydrogenation of unprotected enamino esters and amides is described. Catalyzed by Rh complexes with Josiphos-type chiral ligands, this method gives beta-amino esters and amides in high yield and high ee (93-97% ee). No acyl protection/deprotection is required.
描述了未保护的烯氨基酯和酰胺的直接不对称氢化。该方法由具有 Josiphos 型手性配体的 Rh 络合物催化,以高产率和高 ee (93-97% ee) 得到 β-氨基酯和酰胺。不需要酰基保护/脱保护。
Process for preparing 4-hydroxypyrimidine
申请人:UBE INDUSTRIES, LTD.
公开号:EP0326389A2
公开(公告)日:1989-08-02
A process for preparing a 4-hydroxypyrimidine of Formula III:
wherein R₁ and R₂ each represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms or an aralkyl group having 1 to 10 carbon atoms, and R₄ represents an alkyl group having 7 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an aralkyl group having 7 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms,
which comprises subjecting a 3-amino-2-unsaturated carboxylate of Formula 1:
wherein R₁ and R₂ are as defined above and R₃ represents an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms or an aralkyl group having 7 to 10 carbon atoms,
and a carboxylic acid amide of Formula II:
R ₄ C O N H ₂
wherein R₄ is as defined above,
to reaction with each other in the presence of a base.
Detection and Elimination of Product Inhibition from the Asymmetric Catalytic Hydrogenation of Enamines
作者:Karl B. Hansen、Thorsten Rosner、Michele Kubryk、Peter G. Dormer、Joseph D. Armstrong
DOI:10.1021/ol051862d
日期:2005.10.1
text] The catalytic asymmetric hydrogenation of enamine amides and esters with catalyst Rh-1a, prepared from ferrocenyl based ligand 1a or 1b and [(COD)RhCl](2), has been shown through kinetic studies to suffer fromproduct inhibition. Enamine ester substrates have also been shown to be incompatible with the amine products of the reaction in methanol. In situ protection of the amine products with di-tert-butyl