77290-52-9Relevant academic research and scientific papers
A Concise Synthesis of Sterically Hindered 3-Amino-2-Oxindoles
O'Connor, Stephen J.,Liu, Zheng
, p. 2135 - 2138 (2007/10/03)
A new method for the synthesis of 3-alkyl-3-amino-2-oxindoles is reported. These compounds are prepared in a 3-step procedure using a base-mediated nucleophilic addition of benzylidene-imine protected α-aminoesters to 2-nitrofluorobenzene as the key step. The process provides a variety of 3-alkyl-3-amino-2-oxindole analogs in yields of 1-24%. Yields are highest with alanine, phenylalanine and 2-pyridylalanine as the amino acid starting materials, while 3-pyridylalanine and O-methyltyrosine are less efficiently arylated. Sterically hindered amino acids such as valine and phenylglycine are for all practical purposes, not substrates for the key nucleophilic substitution reaction. The resulting 3-alkyl-3-amino-2-oxindoles are important intermediates for the preparation of drug-like substances. The conversion of alanine ethyl ester to 3-amino-3-methyl-2-oxindole is described.
A convenient synthesis of protected (R)-α-phenylproline derivatives using the Mitsunobu reaction
Van Betsbrugge,Tourwe,Kaptein,Kierkels,Broxterman
, p. 9233 - 9240 (2007/10/03)
Boc-(R)-α-phenylproline ethyl ester 1 was prepared in good yield starting from racemic phenylglycine. Condensation of phenylglycine ethyl ester with benzaldehyde furnished N-benzylidene phenylglycine ethyl ester which was allylated under phase transfer catalysis conditions. After acidic hydrolysis, tile resulting α-allylphenylglycine ethyl ester was enzymatically resolved using PLE. Hydroboration and oxidation of the double bond, Boc-protection and subsequent ring closure using the Mitsunobu reaction protocol gave rise to Boc-(R)-α-phenylproline ethyl ester.
Schiff bases of amino acid esters as new substrates for the enantioselective enzymatic hydrolysis and accompanied asymmetric transformations in aqueous organic solvents
Parmar, Virinder S.,Singh, Amarjit,Bisht, Kirpal S.,Kumar, Naresh,Belokon,Kochetkov,Ikonnikov,Orlova,Tararov,Saveleva
, p. 1223 - 1226 (2007/10/03)
The enzyme (lipases and chymotrypsin)-catalyzed hydrolysis of Schiff bases derived from racemic amino acid esters and aromatic aldehydes has been investigated. The reactions were successfully carried out in different aqueous organic solvents at ambient temperature, but the aqueous acetonitrile (5.4% water content by volume) was the solvent of choice. The L-amino acid (ee 98%) precipitated out from the solution as the reaction progressed, and the liberated aldehyde and unhydrolyzed D-ester (ee 40-98%) remained in the solution. The range of substrates included amino acids having different types of side chains. The addition of an organic base (DABCO) into the solution resulted in the racemization of the remaining D-ester and the additional hydrolysis of the substrate, thus leading to the effective asymmetric transformation of the initial ester. Upto 87.5% of the initial racemate was converted into the L-enantiomer.
New pyrrolidin-, piperidin- and azepin-2-oxocarboxylic acid esters are preferential M1, M3 muscarinic antagonists. Synthesis and bronchospasmolytic activity
Cereda,Ezhaya,Bellora,Schiavi,Sagrada,Doods,Donetti
, p. 411 - 421 (2007/10/02)
A series of new 3-tropanol and 3-quinuclidinol esters of phenyl-substituted pyrrolidin-, piperidin- and azepin-2-oxocarboxylic acid were synthesized and tested for antimuscarinic activity. The compounds showed a preferential in vitro activity at M1 and M3 receptor subtypes and an interesting activity profile in vivo. A potential use as selective bronchospasmolytic agents has been suggested for selected compounds.
Derecemization par protonation enantioselective. Application a un α-aminoacide, la phenylglycine
Duhamel, Lucette,Plaquevent, Jean-Christophe
, p. 75 - 83 (2007/10/02)
This work describes the application of deracemization by enantioselective protonation to α-aminoacid derivatives.Esters of phenylglycine are readly converted into Schiff bases.Melanation of the latter by a lithium amide, followed by protonation by a chiral acid, leads to the optically active starting materials (e.e. as high as 70percent).Chiral acids can easily be retrieved after protonation with excellent yields and conservation of enantiomeric purity.A mechanism responsible for the asymmetric induction is suggested by means of a study of the parameters modifying the selectivity, such as the nature of protecting groups, chiral acid, and lithium amide.
The Reaction of Pyruvic Acid with Amines and Aminoesters Rexamined
Bradamante, Silvia,Colombo, Silvana,Pagani, Giorgo A.,Roelens, Stefano
, p. 568 - 571 (2007/10/02)
Phenylglicine esters react with pyruvic acid to give α-methylsuccinic amides 9 instead of the expected Schiff bases 8, analogously to p-anisidine but unlike aniline.
