Cobley, Christopher J.; Lennon, Ian C.; Praquin, Celine; Zanotti-Gerosa, Antonio; Appell, Robert B.; Goralski, Christian T.; Sutterer, Angela C. published the artcile< Highly Efficient Asymmetric Hydrogenation of 2-Methylenesuccinamic Acid Using a Rh-DuPHOS Catalyst>, Recommanded Product: (S)-(+)-4,12-Bis(di(3,5-xylyl)phosphino)-[2.2]-paracyclophane, the main research area is methylsuccinamic acid enantioselective preparation; methylenesuccinamic acid preparation; asym hydrogenation methylenesuccinamic acid rhodium DuPHOS catalyst; chloride residue methylenesuccinamic acid hindrance asym hydrogenation.
Nonracemic 2-methylsuccinamic acid HO2CCHMeCH2CONH2 is prepared efficiently in two steps from itaconic anhydride using an asym. hydrogenation as the key step. Ring opening of itaconic anhydride with an aqueous solution of ammonium hydroxide followed by neutralization with sulfuric acid yields 2-methylenesuccinamic acid HO2CC(:CH2)CH2CONH2 in 53% yield after recrystallization to remove 3-methylenesuccinamic acid present as an impurity. The use of hydrochloric acid in the neutralization step as in previous procedures leads to the presence of chloride residues in the product; hydrogenation of 2-methylenesuccinamic acid containing chloride residues requires higher loadings of catalyst and longer reaction times, although the enantiomeric excess of the 2-methylsuccinamic acid produced is unaffected. Using 0.001 mol% {[(S,S)-Et-DuPHOS]Rh(COD)}+BF4- as the precatalyst for hydrogenation of 2-methylenesuccinamic acid in methanol under 140 atm of hydrogen at 45°, (R)-2-methylsuccinamic acid is obtained in 96% ee. Single-crystal digestion of (R)-2-methylsuccinamic acid obtained from the hydrogenation yields (R)-2-methylsuccinamic acid in >99.5% ee and 77% conversion containing less than 1 ppm rhodium.
Organic Process Research & Development published new progress about Hydrogenation catalysts, stereoselective. 325168-88-5 belongs to class chiral-phosphine-ligands, and the molecular formula is C48H50P2, Recommanded Product: (S)-(+)-4,12-Bis(di(3,5-xylyl)phosphino)-[2.2]-paracyclophane.
Referemce:
Phosphine ligand,
Chiral phosphine ligands in asymmetric synthesis. Molecular structure and absolute configuration of (1,5-cyclooctadiene)-(2S,3S)-2,3-bis(diphenylphosphino)butanerhodium(I) perchlorate tetrahydrofuran solvate