189098-10-0Relevant articles and documents
Cinchona Alkaloid-Lewis Acid Catalyst Systems for Enantioselective Ketene-Aldehyde Cycloadditions
Zhu, Cheng,Shen, Xiaoqiang,Nelson, Scott G.
, p. 5352 - 5353 (2004)
Asymmetric cinchona alkaloid-catalyzed acid chloride-aldehyde cyclocondensation (AAC) reactions afford enantioenriched 4-substituted and 3,4-disubstituted β-lactones with near perfect absolute and relative stereocontrol. These reactions are characterized
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.
Diastereoselective radical debromination approach toward divergent syntheses of syn- and anti-propionate units, coupled with enantioselective and/or diastereoselective Lewis acid-promoted aldol reactions
Kiyooka, Syun-Ichi
, p. 2897 - 2910 (2007/10/03)
A practical methodology directed to the enantioselective synthesis of polypropionate backbones, available for the synthesis of polyketide natural products, has been developed by iterative enantio- and diastereoselective Lewis acid-promoted aldol reactions, followed by diastereoselective radical debromination reactions. A chiral oxazaborolidinone-promoted aldol reaction of a racemic aldehyde, derived from 2-methyl-1,3-propanediol, with a silylketene acetal from ethyl 2-bromopropionate, resulted in highly enantioselective formation of the corresponding bromo aldol adduct, followed by radical debromination with Bu3SnH in the presence of Et3B to divergently give syn- and anti-propionate aldols, which are versatile stereotriads. Furthermore, elongation of the propionate units has also been achieved: the BF3·OEt2-promoted aldol reaction of chiral syn- and anti-α-methyl-β-protected-oxy aldehydes with the silyl nucleophile proceeded with essentially complete syn-selectivity while the TiCl4-promoted aldol reaction resulted in fairly good anti-selectivity. The resulting bromo aldol adducts were divergently debrominated by the radical reduction to give a complete set of stereotetrads.
Enantio- and diastereoselective reductive aldol reactions with iridium-pybox catalysts
Zhao, Cun-Xiang,Duffey, Matthew O.,Taylor, Steven J.,Morken, James P.
, p. 1829 - 1831 (2007/10/03)
(formula presented) A catalytic amount of [(cod)IrCl]2 and indane-pybox converts diethylmethylsilane, methyl acrylate, and certain aldehydes to the derived reductive aldol adduct with good enantio- and diastereocontrol.
Enantioselective aldol reaction using bornane-2,3-diol-aluminum complex as a chiral Lewis acid
Shimizu, Makoto,Kawamoto, Manabu,Yamamoto, Yasushi,Fujisawa, Tamotsu
, p. 501 - 502 (2007/10/03)
β-Hydroxy ester was formed in high enantiomeric excess by the reaction of ketene silyl acetal with aldehyde in the presence of a chiral Lewis acid prepared from diethylaluminum chloride and chiral diol derived from (+)-camphor.
(S)-Ethyl 4,4-dimethyl pyroglutamate as a new 'quat' chiral auxiliary in aldol condensations
Ezquerra, Jesus,Rubio, Almudena,Martin, Justina,Navio, Jose Luis Garcia
, p. 669 - 671 (2007/10/03)
Enolates I, derived from the N-propionyl derivative of the 'quat' chiral auxiliary (S)-ethyl 4,4-dimethyl pyroglutamate 4 undergo highly stereoselective aldol reactions, which upon hydrolysis and removal of the chiral auxiliary yields the (2R,3R)-3-hydrox
