Pd-catalyzed enantioselective synthesis of quaternary α-amino acid derivatives using a phenylalanine-derived P-chirogenic diaminophosphine oxide
摘要:
A Pd-catalyzed enantio selective synthesis of quaternary alpha-amino acid derivatives using a phenylalanine-derived P-chirogenic diaminophosphine oxide is described. Asymmetric allylic substitution using acyclic beta-keto esters with a nitrogen functional group at the alpha-carbon as prochiral nucleophiles proceeded in the presence of 5 mol % of Pd catalyst, 10 mol % of chiral diaminophosphine oxide 1j, BSA, and appropriate additives, affording the corresponding quaternary alpha-amino acid derivatives in excellent yield and in up to 92% ee. (c) 2007 Elsevier Ltd. All rights reserved.
Development of a New Class of Chiral Phosphorus Ligands: P-Chirogenic Diaminophosphine Oxides. A Unique Source of Enantioselection in Pd-Catalyzed Asymmetric Construction of Quaternary Carbons
phosphorus compounds have been successfully applied to Pd-catalyzed asymmetric construction of tertiary and quaternary carbons. The actual ligand structure was the trivalent phosphorus species 17, which was generated in situ by BSA-induced P(V) to P(III) transformation of 6, the preligand. Detailed mechanistic studies, including asymmetric amplification and initial rate kinetics, revealed that complex 18
Applications of 4,4‘-(Me<sub>3</sub>Si)<sub>2</sub>-BINAP in Transition-Metal-Catalyzed Asymmetric Carbon−Carbon Bond-Forming Reactions
作者:Masamichi Ogasawara、Helen L. Ngo、Takeshi Sakamoto、Tamotsu Takahashi、Wenbin Lin
DOI:10.1021/ol050834s
日期:2005.7.1
A recently developed BINAP derivative with trimethylsilyl substituents on the 4- and 4 '-positions of the binaphthyl skeleton, 2,2 '-bis-(diphenylphosphino)-4,4 '-bis(trimethylsilyl)-1,1 '-binaphthyl (tms-BINAP), was used in a variety of transition-metal-catalyzed asymmetric carbon-carbon bond-forming reactions. In pi-allylpalladium-mediated reactions, tms-BINAP gave better enantioselectivity than the unsubstituted BINAP, and the origin of the improved enantioselectivity was gained from an X-ray structural study of [Pd(eta(3)-C3H5)((R)-tms-BINAP)]CIO4.