7260-27-7Relevant articles and documents
Benzotetramisole-catalyzed dynamic kinetic resolution of azlactones
Yang, Xing,Lu, Guojian,Birman, Vladimir B.
scheme or table, p. 892 - 895 (2010/04/29)
(Figure Presented) Enantioselective acyl transfer catalyst benzotetramisole (BTM) has been found to promote dynamic kinetic resolution of azlactones providing di(1-naphthyl)methyl esters of α-amino acids with up to 96% ee.
Effecient kinetic resolution of racemic amino aldehydes by oxidation with N-iodosuccinimide
Minato, Daishirou,Nagasue, Yoko,Demizu, Yosuke,Onomura, Osamu
supporting information; experimental part, p. 9458 - 9461 (2009/05/06)
(Chemical Equation Presented) Selective recognition: The first efficient method for the kinetic resolution of racemic amino aldehydes (see scheme, PG=protecting group) is based on a copper(II)/(R,R)-Ph-BOX complex. The coordinated amino aldehydes were tra
Asymmetric electrochemical oxidation of 1,2-diols, aminoalcohols, and?aminoaldehydes in the presence of chiral copper catalyst
Minato, Daishirou,Arimoto, Hitomi,Nagasue, Yoko,Demizu, Yosuke,Onomura, Osamu
, p. 6675 - 6683 (2008/12/20)
Asymmetric oxidation of 1,2-diols, aminoalcohols, and aminoaldehydes in the presence of copper(II) triflate and (R,R)-Ph-BOX was accomplished by electrochemical method using Br- as a mediator. This oxidation was applicable to kinetic resolution of racemic cis-cycloalkane-1,2-diols, aminoalcohols, and aminoaldehydes to afford optically active compounds with good to high enantioselectivity.
Molecular recognition on crystallization of enantiopure and racemic N-benzoylalanine methyl ester
Coghlan, Daniel R.,Easton, Christopher J.,Tiekink, Edward R. T.
, p. 551 - 556 (2007/10/03)
The melting points of crystals of (S)- and (RS)-N-benzoylalanine methyl ester derived from solutions of ethyl acetate/light petroleum are 56-57.5° and 81.5-82.5°, respectively, reflecting differences in lattice energy that are apparent from the crystal structures. A more extensive mode of association between chains, uniformly stabilized by N-H?O=C interactions, is found in the racemate leading to a more efficient packing of molecules. The higher lattice energy of the racemate has been confirmed through the enantiomeric enrichment of an optically active sample and the partial resolution of (RS)-N-benzoyl(2-2H)alanine methyl ester, through molecular recognition on crystallization. CSIRO 2000.
Enantioselective enolate protonation: Matching chiral aniline and substrate acidity
Vedejs,Kruger,Suna
, p. 7863 - 7870 (2007/10/03)
A comparison of chiral anilines 1a-f in the asymmetric protonation of enolate 15 shows that the optimum ΔpK(a) value (chiral acid vs protonated enolate) for the highest enantioselectivity is ca. 3 (Table 2). An extension of this concept to amino acid enolates was possible, and 1e was found to give the best enantioselectivity (85% ee) with the alanine-derived N-lithioenolate 5a (Table 3). Changes in aniline pK(a) due to variation of substituents at the aniline nitrogen were evaluated briefly, but these changes did not show consistent trends in the enantioselectivity vs pK(a).
Asymmetric synthesis of uncommon α-amino acids by diastereoselective alkylations of a chiral glycine equivalent
Tanaka, Kiyoshi,Ahn, Mija,Watanabe, Yukari,Fuji, Kaoru
, p. 1771 - 1782 (2007/10/03)
For the purpose of practical preparations of a variety of enantiomerically pure uncommon α-amino acids, alkylations of the chiral glycine equivalent 5, which possesses axially chiral binaphthol as an auxiliary, with several electrophiles were investigated. The alkylation proceeded smoothly in satisfactory chemical yield with high diastereo-selectivities to give protected α-amino acid derivatives. The free hydroxyl group of the auxiliary played an important role for the induction of diastereoselectivity. Using (S)-1,1'-binaphthalene-2,2'-diol as a chiral auxiliary, D-α-amino acid derivatives having the unnatural (R)-configuration were predominantly obtained. Some of the alkylated products were converted into free non- proteinogenic D-α-amino acids.
Diastereoselective Diels-Alder Reactions with α-Chloronitroso Saccharides
Braun, Heinz,Felber, Helena,Kresze, Guenter,Schmidtchen, Franz P.,Prewo, Roland,Vasella, Andrea
, p. 261 - 268 (2007/10/02)
The α-chloronitroso reagent 2 obtained from ribose via the lactone oxime 3 reacts with the dienes 6-10 at low temperature to give the chiral dihydrooxazines 11-16 in 63-96percent yield and >/=96percent enantiomeric excess.The reagents 1 and 2 which are ap
Enzymatic Asymmetric Synthesis of α-Amino Acids. Enantioselective Cleavage of 4-Substituted Oxazolin-5-ones and Thiazolin-5-ones
Crich, Joyce Z.,Brieva, Rosario,Marquart, Peer,Gu, Rui-Lin,Flemming, Steffen,Sih, Charles J.
, p. 3252 - 3258 (2007/10/02)
A general enzymatic asymmetric synthesis of L-α-amino acids has been developed.This method entails the use of the Pseudomonas cepacia lipase (P-30) to catalyze the enantioselective methanolysis of a variety of 4-substituted 2-phenyloxazolin-5-one derivatives in a nonpolar organic solvent to furnish optically active N-benzoyl-L-α-amino acid methyl esters (ee = 66-98 percent), which in turn is subjected to a protease-catalyzed kinetic resolution yielding enantiomerically pure N-benzoyl-L-α-amino acids.This synergistic coupling of two enzymes allows the ready preparation of L-α-amino acids of high enantiopurity in yields greater than 50 percent, an inherent advantage over conventional resolution procedures.Two proteases were found to catalyze the enantioselective hydrolysis of a variety of 4-substituted 2-phenylthiazolin-5-one derivatives to give N-(thiobenzoyl)-L-α-amino acids of high optical purity.
