38574-55-9Relevant academic research and scientific papers
Influence of aromatic substituents on metal(II)salen catalysed, asymmetric synthesis of α-methyl α-amino acids
Achard, Thierry,Belokon', Yuri N.,Fuentes, Jose A.,North, Michael,Parsons, Teresa
, p. 5919 - 5930 (2004)
The influence of substituents on both the aromatic rings of the catalyst, and the benzylidene unit of the substrate are investigated in the (salen)copper(II) catalysed asymmetric benzylation of alanine derivatives. Catalysts with electron-donating, and el
Chiral salen ligands designed to form polymetallic complexes
Achard, Thierry R.J.,Clegg, William,Harrington, Ross W.,North, Michael
experimental part, p. 133 - 144 (2012/01/06)
Chiral salen ligands capable of forming polymetallic complexes have been designed. The ligands possess substituents in the 4,4′-positions, but have no substituent in the 3,3′-positions to allow a second metal ion access to the salen oxygen atoms. Ligands in which a polyether chain links the 4,4′-positions were prepared and complexed to copper. In addition, acyclic ligands with potential metal coordinating substituents in the 4,4′-positions were prepared and complexed to copper and cobalt. The crystal structure of one of the cobalt complexes shows it to be a trimetallic complex in which a Co(II)(OAc)2 group coordinates to the salen oxygen atoms of two Co(III)(salen)(OAc) units. In contrast, the crystal structure of a Co(salen) complex with tert-butyl groups attached to the 3,3′-positions is found to be mononuclear. All of the complexes were tested as asymmetric phase transfer catalysts for the asymmetric alkylation of an alanine methyl ester, forming (R)-α-methyl phenylalanine methyl ester with up to 85% ee.
Asymmetric catalysis of carbon-carbon bond forming reactions using amino acid-derived C1-symmetrical salen ligands
Belokon, Yuri N.,Hunt, Jamie,North, Michael
experimental part, p. 2804 - 2815 (2009/06/28)
Four amino acids (alanine, valine, phenylalanine and phenylglycine) have been converted into C1-symmetrical salen ligands and complexed to titanium, vanadium, copper and cobalt. The resulting complexes have been used as asymmetric catalysts for asymmetric cyanohydrin synthesis, asymmetric Strecker reactions, asymmetric synthesis of α-methyl amino acids and asymmetric Darzens condensations. Satisfactory levels of asymmetric induction were obtained from reactions in which the (salen)metal complex acts as a chiral Lewis acid, but low levels of asymmetric induction were obtained from reactions carried out under solid-liquid phase-transfer conditions.
Diastereoselective synthesis of quaternary α-amino acids from diketopiperazine templates
Davies, Stephen G.,Christopher Garner,Ouzman, Jaqueline V. A.,Roberts, Paul M.,Smith, Andrew D.,Snow, Emma J.,Thomson, James E.,Tamayo, Juan A.,Vickers, Richard J.
, p. 2138 - 2147 (2008/03/14)
Sequential enolate alkylations of (S)-N(1)-methyl-5-methoxy-6-isopropyl-3, 6-dihydropyrazin-2-one and (S)-N(1)-p-methoxybenzyl-5-methoxy-6-isopropyl-3,6- dihydropyrazin-2-one proceed with excellent levels of diastereoselectivity (>90% de) affording quaternary α-amino acids in high enantiomeric excess (>98% ee) after deprotection and hydrolysis. This journal is The Royal Society of Chemistry.
Influence of the metal and chiral diamine on metal(II)salen catalysed, asymmetric synthesis of α-methyl α-amino acids
Belokon, Yuri N.,Fuentes, Jose,North, Michael,Steed, Jonathan W.
, p. 3191 - 3204 (2007/10/03)
The influence of the metal ion and chiral diamine used to form a metal(salen) complex on the catalytic activity of the complex in the asymmetric benzylation of an alanine enolate was investigated. Only metal ions which could form square-planar complexes g
The influence of imine structure, catalyst structure and reaction conditions on the enantioselectivity of the alkylation of alanine methyl ester imines catalyzed by Cu(ch-salen)
Belokon', Yuri N.,Davies,Fuentes, Jose A.,North, Michael,Parsons, Teresa
, p. 8093 - 8096 (2007/10/03)
Systematic variation of the substrate structure has shown that the most effective substrates for Cu(ch-salen)-catalyzed asymmetric enolate alkylation reactions carried out under phase-transfer conditions are the para-chlorophenyl imines of amino esters. T
A practical asymmetric synthesis of α-methyl α-amino acids using a chiral cu-salen complex as a phase transfer catalyst
Belokon',Davies,North
, p. 7245 - 7248 (2007/10/03)
The asymmetric C-alkylation of N-benzylidene alanine methyl ester has been achieved using a copper(II) (salen) complex as an asymmetric phase transfer catalyst and provides a practical synthesis of α-methyl α-amino acids with up to 86% enantiomeric excess. (C) 2000 Elsevier Science Ltd.
2-Methyl N-(p-toluenesulfinyl)aziridine-2-carboxylic acid: Asymmetric synthesis of α-methylphenylalanine and α-methyl-β-phenylserine
Davis, Franklin A.,Liu, Hu,Reddy, G. Venkat
, p. 5473 - 5476 (2007/10/03)
2-Substituted aziridine 2a, prepared from sulfinimine 1 via a Darzens-type condensation, undergoes a highly regio- and stereocontrolled ring-opening to give α-methylphenylalanine and α-methyl-β-phenylserine in high enantiomeric purity.
ASYMMETRIC SYNTHESIS OF β-HYDROXY-α-ALKYLAMINO ACIDS BY ASYMMETRIC ALDOL REACTION OF α-ISOCYANOCARBOXYLATES CATALYZED BY CHIRAL FERROCENYLPHOSPHINE-GOLD(I) COMPLEXES
Ito, Yoshihiko,Sawamura, Masaya,Shirakawa, Eiji,Hayashizaki, Keiichi,Hayashi, Tamio
, p. 5253 - 5262 (2007/10/02)
Aldol reaction of methyl α-isocyanocarboxylates (CNCH(R)COOMe: R = H, Me, Et, i-Pr) with benzaldehyde or acetaldehyde in the presence of 0.5-1.0 molpercent of a chiral (aminoalkyl)ferrocenylphosphine-gold(I) complex gave optically active 4-methoxycarbonyl
REACTIONS OF SCHIFF BASE ANIONS WITH ELECTROPHILES: ROLE OF THE INITIAL STEREOCHEMISTRY
El Achqar, Abdelrhani,Roumestant, Marie-Louise,Viallefont, Philippe
, p. 2441 - 2444 (2007/10/02)
It is shown that the reactivity towards electrophiles of diastereomeric Schiff bases of *R and *S valine, leucine, phenylalanine and norvaline methyl esters with (1S,2S,5S) or (1R,2R,5R) 2-hydroxy 3-pinanone, is highly dependent on the stereochemistry of the starting product.
