16367-69-4

Upstream product

• 16975-59-0 2-(2,2,2-Trifluoro-acetylamino)-propionic acid tert-butyl ester 
• 81477-94-3 N-(diphenylmethylene)glycine tert-butyl ester 
• 74-88-4 methyl iodide 
• 226900-13-6 tert-butyl N-(diphenylmethylene)alaninate 
• 76849-54-2 t-butyl pyruvate 

Downstream Products

• 64923-14-4 2-[(2S,5R)-2-Isopropyl-5-methyl-cyclohex-(E)-ylideneamino]-propionic acid tert-butyl ester 
• 106927-29-1 tert-butyl 2-(benzamido)propanoate 
• 245338-80-1 N-(phenylmethylene)alanine t-butyl ester 
• 1325726-84-8 2-[2-(4-bromophenyl)-5-methyl-1H-pyrrol-1-yl]propionic acid tert-butyl ester 
• 1325726-74-6 2-(2-methyl-5-phenyl-1H-pyrrol-1-yl)propionic acid tert-butyl ester 
• 59624-88-3 N-Benzoyl-L-alanin-tert.-butylester 
• 35320-23-1 (R)-2-aminopropan-1-ol 

Relevant academic research and scientific papers

Asymmetric Synthesis of α-Amino Acids by Organocatalytic Biomimetic Transamination

A biomimetic enantioselective transamination of α-keto ester derivatives can be realized under mild conditions by using chiral quaternary ammonium arenecarboxylates in the absence of base additives. The corresponding α-amino acids can be used as versatile intermediates for further synthetic transformations that furnish chiral pyrrolidine and octahydroindolizine derivatives.

Recoverable Dendritic Phase-Transfer Catalysts that Contain (+)-Cinchonine-Derived Ammonium Salts

Four new phosphorus dendrimeric phase-transfer catalysts are prepared that contain 12 (+)-cinchoninium salts on the surface obtained by the quaternisation of the quinuclidinic N atom. The asymmetric alkylation of a glycinate Schiff base with benzyl bromide is used as a benchmark reaction, and the dendrimeric catalyst that contains an allyl group on the O-9 hydroxy group of the cinchonine units is the most active. The recovery and reuse of the catalyst are possible for five consecutive runs without loss of activity and with only a slight decrease in enantioselectivity. If other electrophiles are used, substituted benzyl bromides give better results than other activated alkyl bromides to afford the corresponding R amino acid derivatives. A comparison of these results with those reported previously for similar cinchoninium salts shows that dendrimers could be a better support than other polymers for this type of organocatalysis.

A cyclic hexapeptide comprising alternating α-aminoxy and α-amino acids is a selective chloride ion receptor

In nonpolar solvents, the cyclic hexapeptide 2, which comprises alternating D-α-amino and D-α-aminoxy acids, adopts a C3-symmetric conformation with alternating eight (N-O turns)- and seven (γ turns)-membered-ring hydrogen bonds. A series of anion-binding studies has suggested that 2 can function as an effective anion receptor that not only displays a high selectivity for chloride ions, but also the capability to extract chloride ions from aqueous solutions into organic phases.

Studies on the enantioselective synthesis of α-amino acids via asymmetric phase-transfer catalysis

In this paper, we describe investigations into the use of cinchona alkaloid-derived quaternary ammonium phase-transfer catalysts for the asymmetric alkylation of a benzophenone-derived glycine-imine. Utility of this process is demonstrated by the enantioselective synthesis of a range of α-amino acid esters.

Comparative conformational analysis of peptides based on the two Ca-tetrasubstituted, Cβ-branched, chiral α-amino acids (αMe) Dip and (αMe)Val

For the first time a number of terminally protected model peptides (to the pentamer level) of the sterically demanding α-amino acid Cα-methyl, Cα-diphenylmethylglycine, (αMe)Dip, in combination with either Ala or Gly residues, have been synthesized (by solution methods) and fully characterized. In a parallel synthesis the corresponding peptides based on the related α-amino acid Cα-methyl, Cα-isopropylglycine, (αMe)Val, have also been prepared. The results of a comparative conformational analysis, performed by using FTIR absorption, 1H NMR, and X-ray diffraction techniques, favour the conclusion that, in contrast to the potent β-turn and 310-helix promoter (αMe)Val, (αMe)Dip may induce either a folded or a fully extended conformation. These findings indicate that, despite the common Cα-methylated and Cβ-branched features, (αMe)Dip and (αMe)Val are characterized by partially divergent conformational bias.

A new class of asymmetric phase-transfer catalysts derived from Cinchona alkaloids - Application in the enantioselective synthesis of α-amino acids

A new class of Cinchona alkaloid-derived quaternary ammonium phase-transfer catalysts bearing a N-anthracenylmethyl function are presented. These catalysts show high stereocontrol in the asymmetric alkylation of a benzophenone-derived glycine-imine, and application of this process to the enantioselective synthesis of a range of α-amino acid esters (e.e. 67-94%) is investigated.

Chemoselective N-deprotection of tert-butyl 2-(trifluoroacetylamino) esters under PTC conditions: Synthesis of tert-butyl 2-aminocarboxylates

Trifluoroacetamide 1 is alkylated in good yields (77-83%) by tert-butyl 2-bromocarboxylates 3 under solid-liquid phase transfer catalysis (PTC) conditions [anhydrous K2CO3, triethyl(benzyl)ammonium chloride (TEBA; 10%), MeCN, 80°C]. The resulting tert-butyl 2-(trifluoroacetylamino) carboxylates 5 are chemoselectively hydrolysed in 75-95% yields to the corresponding tert-butyl 2-amino carboxylates, isolated as hydrochlorides 8, under liquid-liquid PTC conditions [CH2Cl2 or Et2O, aqueous 20% KOH, TEBA (10%), 25-40°C].