36567-72-3Relevant articles and documents
Sterically congested chiral N-acetyl 2-oxazolidinone as acetyl enolate equivalents in stereoselective aldol reactions
Otsuka,Ishizuka,Kimura,Kunieda
, p. 748 - 750 (1994)
Sterically constrained and highly congested N-acetyl-DMAOx (1a) serves well as a useful chiral acetyl enolate equivalent which permits a diastereoselective and direct approach to 'acetate' aldols (2) including statine derivative.
Solvent-induced chirality switching in the enantioseparation of regioisomeric hydroxyphenylpropionic acids via diastereomeric salt formation with (1R,2S)-2-amino-1,2-diphenylethanol
Kodama, Koichi,Nagata, Jun,Kurozumi, Nobuhiro,Shitara, Hiroaki,Hirose, Takuji
, p. 460 - 466 (2017/03/23)
The enantioseparation of three hydroxyphenylpropionic acid isomers via diastereomeric salt formation with (1R,2S)-2-amino-1,2-diphenylethanol has been demonstrated. The racemates of all three acid isomers were successfully separated with high efficiency (0.56–0.84) after single crystallization. For 2-hydroxy-3-phenylpropionic acid 4, the configuration of the less-soluble salt was controlled by the crystallization solvent: the (R)-4 salt was crystallized from water, while 2-propanol afforded the (S)-4 salt. The chiral recognition mechanism of the three acids was discussed based on the crystal structures of the diastereomeric salts.
Substrate evaluation of rhodococcus erythropolis SET1, a nitrile hydrolysing bacterium, demonstrating dual activity strongly dependent on nitrile sub-structure
Coady, Tracey M.,Coffey, Lee V.,O'Reilly, Catherine,Lennon, Claire M.
supporting information, p. 1108 - 1116 (2015/02/19)
Assessment of Rhodococcus erythropolis SET1, a novel nitrile hydrolysing bacterial isolate, has been undertaken with 34 nitriles, 33 chiral and 1 prochiral. These substrates consist primarily of β-hydroxy nitriles with varying alkyl and aryl groups at the β position and containing in several compounds different substituents α to the nitrile. In the case of β-hydroxy nitriles without substitution at the α position, acids were the major products obtained, along with recovered nitrile after biotransformation, as a result of suspected nitrilase activity of the isolate. Unexpectedly, amides were found to be the major hydrolysis product when the β-hydroxy nitriles possessed a vinyl group at this position. To probe this behaviour further, additional related substrates were evaluated containing electron-withdrawing groups at the α position, and amide was also observed upon biotransformation in the presence of SET1. Therefore this novel isolate has also demonstrated NHase activity with nitriles that appears to be substrate-dependent.
Stereoselective acetate aldol reactions of α-silyloxy ketones
Lorente, Adriana,Pellicena, Miquel,Romea, Pedro,Urpí, Fèlix
, p. 1023 - 1035 (2015/01/30)
TiCl4-mediated aldol reactions of chiral methyl α-silyloxy ketones with a variety of aldehydes provide the corresponding 1,4-syn aldol adducts with moderate to high stereocontrol. This transformation represents a new approach to substrate-controlled acetate aldol reactions and complements the 1,4-anti asymmetric induction produced by the related α-benzyloxy ketones. This new approach could be useful in the design of more efficient syntheses of natural products.
Biotransformation of aromatic ketones and ketoesters with the non-conventional yeast Pichia glucozyma
Contente, Martina Letizia,Molinari, Francesco,Zambelli, Paolo,De Vitis, Valerio,Gandolfi, Raffaella,Pinto, Andrea,Romano, Diego
supporting information, p. 7051 - 7053 (2015/02/02)
The non-conventional yeast Pichia glucozyma CBS 5766 has been used for the biotransformation of different aromatic ketones and ketoesters. The growth and biotransformation conditions were optimised for the reduction of acetophenone and under optimised conditions, propiophenone, butyrophenone and valerophenone were reduced to the corresponding (S)-alcohols with high yields and enantioselectivity. Ketoreductase(s) of Pichia glucozyma showed high catalytic activities also towards aromatic β- and γ-ketoesters, being often competitive with esterase(s). These concurrent activities allowed for the preparation of hydroxyesters, hydroxyacids and lactones often in a very selective manner.
Studies toward stereoselective bionanocatalysis on gold nanoparticles
Jedrzejewska, Hanna,Ostaszewski, Ryszard
, p. 12 - 16 (2013/05/09)
As yet, different enzymes were immobilized on gold nanoparticles both through adsorption and covalent binding. However, there is only one evaluation if such immobilization influenced enzyme enantioselectivity, which is an essential parameter in biocatalys
Asymmetric β-boration of α,β-unsaturated N -acyloxazolidinones by [2.2]paracyclophane-based bifunctional catalyst
Zhao, Lei,Ma, Yudao,Duan, Wenzeng,He, Fuyan,Chen, Jianqiang,Song, Chun
, p. 5780 - 5783 (2013/01/15)
An efficient copper-catalyzed asymmetric conjugate boration has been achieved by exploiting a new planar and central chiral bicyclic triazolium ligand. This protocol was highly efficient and gave a variety of chiral secondary alkylboronates in 97-99% ee. A preliminary mechanistic study supports the bifunctional nature of the catalyst.
Reversal of selectivity in acetate aldol reactions of N-acetyl-(S)-4- isopropyl-1-[(R)-1-phenylethyl]imidazolidin-2-one
Khatik, Gopal L.,Kumar, Varun,Nair, Vipin A.
scheme or table, p. 2442 - 2445 (2012/07/03)
Synergistic effects of the exo- and endocyclic chiral centers of an imidazolidinone-based auxiliary were investigated in the perspective of acetate aldol reactions. The reversal in diastereoselectivity was accomplished by lithium and titanium enolate reactions, which proceed through proposed open and closed transitions states, respectively. The aldol adducts were used in the stereoselective synthesis of fluoxetine.
Rhodium-catalyzed asymmetric addition of arylboroxines to β-alkoxyacrylate esters
Nishimura, Takahiro,Kasai, Atsuyuki,Nagaosa, Makoto,Hayashi, Tamio
supporting information; experimental part, p. 10488 - 10490 (2011/12/04)
Asymmetric addition of arylboroxines to β-alkoxyacrylate esters proceeded in the presence of a rhodium complex coordinated with a chiral diene ligand to give high yields of β-alkoxy-β-arylcarboxylic acid esters with very high enantioselectivity.
1,4-syn-Asymmetric induction in the titanium-mediated aldol reactions of chiral methyl α-silyloxy ketones
Lorente, Adriana,Pellicena, Miquel,Romea, Pedro,Urpí, Fèlix
scheme or table, p. 942 - 945 (2010/04/29)
Good levels of 1,4-syn asymmetric induction are obtained in the TiCl4-mediated aldol reaction of methyl α-silyloxy ketones with achiral aldehydes. Such methodology represents a new approach to the substrate-controlled acetate aldol reaction, which can be useful to design more efficient syntheses of natural products.