20850-40-2

Upstream product

• 66789-45-5 (Z)-2-acetamido-3-(3,4-methylenedioxyphenyl)acrylic acid 
• 120-57-0 piperonal 
• 60470-83-9 2-methyl-4-(3,4-methylenedioxyphenylmethylene)-5(4H)-oxazolone 
• 51703-92-5 N-acetyl-(R,S)-3,4-methylenedioxyphenylalanine methyl ester 
• 41888-62-4 4-benzo[1,3]dioxol-5-ylmethylene-2-methyl-4H-oxazol-5-one 

Relevant academic research and scientific papers

Synthesis of a novel spiro bisphosphinite ligand and its application in Rh-catalyzed asymmetric hydrogenation

A novel, chiral bisphosphinite ligand (R)-SpiroBIP has been synthesized. The rhodium complex of the ligand was found to be highly enantioselective in the asymmetric hydrogenation of α-dehydroamino acid derivatives.

Synthesis and application of (3R,4R)-3,4-bis(diphenylphosphino)tetrahydrofuran as ligand for asymmetric hydrogenation of acrylic acids

A new, chiral bisphosphine, (3R,4R)-3,4-bis(diphenylphosphino)tetrahydrofuran (4), is synthesized in three steps from (R,R)-tartaric acid esters. With rhodium(I) complexes of 4 enantiomeric excesses of 54 to 97% are obtained on catalytic hydrogenation of 2-(acetylamino)acrylic acid, 2-(acetylamino)cinnamic acids and itaconic acid. The applied substrate/catalyst ratios were between 250:1 and 11,000:1.

Synthesis of (S)-3,4-dihydroxyphenylalanine (L-DOPA) and unnatural α-amino acids via enzymatic resolution using alcalase

Enzymatic resolution has been used for the synthesis of L-DOPA with high optical purity.N-Acetyl-(R,S)-3,4-methylenedioxyphenylalanine methyl ester (2b) on enzymatic resolution by alcalase (Subtilisin Carlsberg) yields N-acetyl-(S)-3,4-methylenedioxyphenylalanine (3b) which upon acid treatment affords (S)-3,4-dihydroxyphenylalanine (L-DOPA) (4).Several optically active unnatural N-acetylated and N-benzoylated α-amino acids have been prepared by similar enzymatic resolution.

Asymmetric Hydrogenation of 3,4-Methylenedioxy-α-acetamidocinnamic Acid Using Newly Developed Silica Gel-Supported Chiral Rhodium(I)-Phosphine Complexes

The asymetric hydrogenation of 3,4-methylenedioxy-α-acetamidocinnamic acid was carried out in the presence of a chiral Rh(l)-complex of (2S,4S)-N-butoxycarbonyl-4-diphenylphosphino-2-diphenylphosphinomethylpyrrolidine (BPPM) adsorbed on hydrophobic silica

Enantioselective Catalysis, 4. Synthesis of N-Substituted (R,R)-3,4-Bis(diphenylphosphino)pyrrolidines. The Use of their Rhodium Complexes for the Asymmetric Hydrogenation of α-(Acylamino)acrylic Acid Derivatives

A simple synthesis of (R,R)-3,4-bis(diphenylphosphino)pyrrolidine (6a) and some N-substituted derivatives 6b-m is described. 6l and 6m are optically active tetraphosphanes, composed of two (R,R)-3,4-bis(diphenylphosphino)pyrrolidine units and a dicarboxylic residue.The structure of the parent compound 6a was determined by X-ray diffraction.From the phosphanes 6a-m the cationic 1,5-cyclooctadiene-bisphosphane-rhodium complexes 7a-m were prepared.The complexes 7l and 7m are ligand bridged bis(rhodium) dications.The complexes 7a-m were used for the asymmetric catalytic hydrogenation of the α-(acylamino)acrylic acid derivatives 9a-l.Enantiomeric excesses up to 100percent were achieved.Between 1 and 70 at the optical yields do not depend on the hydrogen pressure.The substrate/catalyst ratio can be as high as 50000/1.

Asymmetric Catalyses. V. Enantioselective Amino Acid Synthesis by Hydrogenation of Prochiral Olefins with Rh-Complexes of the New Optically Active Chelating Phosphane Norphos

Racemic bicyclohept-5-ene-2,3-diylbis(diphenylphosphane oxide), NorphosO, can be resolved with (-)-di-O-benzoyltartaric acid, (-)-DBW.The X-ray structure analysis of the diastereomer (-)-NorphosO/(-)-DBW, which is less soluble in ethanol, exhibits strong hydrogen bonds between the carboxylic groups of DBW and the PO groups.The bonding of the DBW-carboxylic groups to different NorphosO units leads to the formation of infinite close-packed chains.From the internal comparison with (-)-DBW the absolute configuration follows as (2R,3R) for (-)-Norphos.The chelating phosphanes (+)- and (-)-Norphos, obtained by SiHCl3-reduction of (+)- and (-)-NorphosO, respectively, afford neutral and cationic Rh-complexes which, with H2 at room temperature and atmospheric pressure within a few hours, give quantitative hydrogenation of α-(acetylamino)cinnamic acid, α-(acetylamino)acrylic acid and Dopa precursors.The optical yields vary between 79 and 97percent.