57043-00-2Relevant academic research and scientific papers
Stereoselective organocatalytic approach to α,β-disubstituted- β-amino acids: A short enantioselective synthesis of cispentacin
Pou, Ana,Moyano, Albert
, p. 3103 - 3111 (2013/06/26)
α-Branched α,β-unsaturated aldehydes have been tested in the organocatalytic tandem Michael addition/cyclization with N-(benzyloxycarbonyl)hydroxylamine, a reaction which until now has been restricted to α-unsubstituted enals. Starting from cyclopentene-2- carbaldehyde, and using diphenylprolinol trimethylsilyl ether as a chiral amine catalyst, this approach has led to the development of a practical, high yielding (93-98 % overall yield, three steps), and highly enantioselective (up to 98:2 er) route to the cyclic β-amino acid cispentacin, which compares favourably with previously described asymmetric syntheses of this biologically active natural product. When using acyclic α-branched α,β-unsaturated aldehydes as substrates, the reaction yields depend on the substitution pattern of the aldehydes, and mixtures of cis- and trans-isomers are obtained. Nevertheless, this strategy has proved to be successful in some instances, and (3R,4R)-benzyl 3-ethyl-4-methyl-5-oxoisoxazolidin-2-carboxylate could be obtained in 70 % overall yield (two steps) from the reaction of 2-ethylcrotonaldehyde and N-(benzyloxycarbonyl)hydroxylamine under catalysis with diphenylprolinol trimethylsilyl ether, and with high enantiomeric purity (99:1 er). The organocatalytic tandem Michael addition/cyclization of cyclopentene-2-carbaldehyde with N-Cbz-hydroxylamine, using diphenylprolinol TMS ether as a chiral amine catalyst, gives a practical, high yielding, and highly enantioselective route to the cyclic β-amino acid cispentacin. Acyclic α-branched enals give variable results in the same reaction, depending on the substitution pattern. Copyright
The first direct enzymatic hydrolysis of alicyclic β-amino esters: A route to enantiopure cis and trans β-amino acids
Forro, Eniko,Fueloep, Ferenc
, p. 6397 - 6401 (2008/02/13)
The first direct enzymatic method is reported for the synthesis of cis and trans βamino acid enantiomers through the lipase-catalyzed enantioselective hydrolysis of alicyclic β esters in organic media. High enantioselectivities (E usually > 001) were observed when the Candida antarctica lipase B catalyzed reactions were performed with H2O (0.5 equivalents) in iP iPr2O at 5°C. The resolved products, obtained in good yields (≥42%), could be easily separated.
A novel preparation of 2-aminocyclopentanecarboxamides
Csomos, Peter,Bernath, Gabor,Fueloep, Ferenc
, p. 1077 - 1084 (2007/10/03)
Different syntheses of cis- and trans-2-aminocyclopentanecarboxamides were studied. A convenient and effective method was devised for the preparation of cis-2-aminocyclopentanecarboxamide derivatives starting from the readily available 6-tert-butoxycarbon
An improved synthesis of enantiopure β-amino acids
Cimarelli,Palmieri,Volpini
, p. 2943 - 2953 (2007/10/03)
An improved method for the preparation of both the enantiopure β-amino acids is presented. The diastereomer benzyl β-amino esters, obtained by stereoselective reduction of β-enamino esters, were separated and hydrogenolyzed to the free enantiopure β-amino acids.
Synthesis of racemic and optically active cispentacin (FR109615) using intramolecular nitrone-olefin cycloaddition
Konosu,Oida
, p. 1012 - 1018 (2007/10/02)
Synthesis of racemic and optically active cispentacin ((-)-1) is described. Intramolecular nitrone-olefin cycloaddition of the alkenyl nitrone 7 gave cis-isoxazolidine (±)-8, which was transformed into (±)-1 by sequential reactions involving catalytic hyd
