122745-11-3Relevant articles and documents
Asymmetric chemoenzymatic synthesis of N-acetyl-α-amino esters based on lipase-catalyzed kinetic resolutions through interesterification reactions
Da Silva, Marcos Reinaldo,De Mattos, Marcos Carlos,De Oliveira, Maria Da Concei??o Ferreira,De Lemos, Telma Leda Gomes,Ricardo, Nágila Maria Pontes Silva,De Gonzalo, Gonzalo,Lavandera, Iván,Gotor-Fernández, Vicente,Gotor, Vicente
, p. 2264 - 2271 (2014/03/21)
Several phenylalanine analogs have been synthesized through a four-step route starting from easily available ethyl acetamidocyanoacetate. In a first reaction, and making use of phase transfer catalysts, this compound reacted with several alkyl halides, being benzyltributylammonium chloride identified as the best one for the production of a series of quaternary amino acids in moderate to excellent yields (52-95%). Then, the corresponding N-acetyl-phenylalanine methyl and allyl ester derivatives were obtained through acidic hydrolysis, esterification, and N-acetylation. Rhizomucor miehei lipase was found as a versatile enzyme for the resolution of these amino esters, finding the best results through interesterification reactions with butyl butyrate in acetonitrile. A great influence in the stereoselectivity was found depending on the chemical structure of the compound, achieving for the non- or para-substituted in the phenyl ring excellent stereoselectivities, being moderate for the meta-nitro derivative, while the ortho-nitro amino ester did not react.
Preparation of chiral amino esters by asymmetric phase-transfer catalyzed alkylations of schiff bases in a ball mill
Nun, Pierrick,Perez, Violaine,Calmes, Monique,Martinez, Jean,Lamaty, Frederic
experimental part, p. 3773 - 3779 (2012/04/23)
The asymmetric alkylation of Schiff bases under basic conditions in a ball mill was performed. The starting Schiff bases of glycine were prepared beforehand by milling protected glycine hydrochloride and benzophenone imine, in the absence of solvent. The Schiff base was then reacted with a halogenated derivative in a ball mill in the presence of KOH. By adding a chiral ammonium salt derived from cinchonidine, the reaction proceeded asymmetrically under phase-transfer catalysis conditions, giving excellent yields and enantiomeric excesses up to 75 %. Because an equimolar amount of starting material was used, purification was greatly simplified. Copyright
Synthesis and biological activity of ketomethylene pseudopeptide analogues as thrombin inhibitors
Cheng,Goodwin,Schully,Kakkar,Claeson
, p. 3364 - 3369 (2007/10/02)
Ketomethylene pseudopeptide analogues Aa-Pro-Argψ(COCH2)Gly-pip, 1, where Aa are D- or L-amino acids (Dpa, β,β-diphenylalanine; αNal, α- naphthylalanine; βNal, β-naphthylalanine; Fgl, fluorenylglycine) with highly lipophilic side chains and ψ(COCH2) is a ketomethylene pseudopeptide bond, have been synthesized through a modified Dakin-West reaction under very mild conditions with a high yield using tripeptide 4 with a labile functional group directly on the side chain. Their enzymatic assay of thrombin inhibition has been carried out. The structure-activity relationship study indicated that a lipophilic side chain on the amino acid in the P3 position is very important for binding to the apolar site of thrombin. Compound 1a with D-Dpa at the P3 position has a K(i) of 0.2 μM and it doubles thrombin clotting time at only 3 times higher concentration. These values are about 7 times better than those of the corresponding D-Phe analogues. Furthermore, 1a shows poor inhibitory activity against plasmin, factor Xa, urokinase, and kallikrein. Preliminary in vivo testing (3-4-kg rabbit as the animal model) shows no observable side effect (change of blood pressure and accumulation of blood platelet in lungs) at a dose of 1 mg/kg.
