176965-33-6Relevant academic research and scientific papers
Efficient Catalytic Enantioselective Reaction of a Glycine Cation Equivalent with Malonate Anions via Palladium Catalysis
O'Donnell, Martin J.,Chen, Ning,Zhou, Changyou,Murray, Angela,Kubiak, Clifford P.,Yang, Fan,Stanley, George G.
, p. 3962 - 3975 (1997)
The enantioselective alkylation of Schiff base acetates 1 with malonate types of stabilized carbon nucleophiles in the presence of a stable palladium source Pd(OAc)2 and the chiral ligand (+)-BINAP was developed. The product 2, a protected β-carboxyaspartic acid (ASA), was obtained in up to 85percent enantiomeric excess by varying the ester protecting group on the substrate. The nature of the nucleophile has a significant effect on the enantioselectivity in this (2-aza-π-allyl)palladium system. While a rapid chemical conversion was achieved with Schiff base benzoates 5, the enantioselectivity was insensitive to the leaving group used. An optically active substrate (51percent ee) gave the same level of enantioselectivity as that obtained from the racemate. Temperature effects on the reaction were also studied; the best selectivity was obtained at 0°C. A laboratory-scale reaction of the reactive nucleophile KCH(COOCH3)2 with the tert-butyl ester substrate le gave, following a single recrystallization, product 2c with 95.5percent ee in an overall chemical yield of 62percent.
Preparation of optically active β-carboxyaspartic acid derivatives via Pd(0)-catalyzed asymmetric substitution of Schiff base acetates
O'Donnell, Martin J.,Zhou, Changyou,Chen, Ning
, p. 621 - 624 (1996)
Optically active β-carboxyaspartic acid derivative 6 (77% ee) was obtained in 48% total yield from the coupling of Schiff base acetate 3 with sodium dimethyl malonate in the presence of 5% Pd(OAc)2-(2S,4S)-BPPM followed by a single recrystalliz
