73440-88-7Relevant articles and documents
Biomimetic Studies Using Artificial Systems. II. Enantioselective Thiolysis of D- or L-α-Amino Acid Ester Salts by Thiol-Bearing Chiral Crown Ethers as an Enzyme Model
Sasaki, Shigeki,Kawasaki, Motoji,Koga, Kenji
, p. 4247 - 4266 (2007/10/02)
The rates of transacylation were studied between thiol-bearing chiral crown ethers (1-10) and α-amino acid p-nitrophenyl ester salts.Enantioselectivities, kD/kL ratios, of 6.5 for valine ester salt, 8.7 for phenylalanine ester salt, and 7.7 for valine ester salt were achieved by 1, 5, and 8, respectively.Saturation phenomena of rate acceleration depending on crown concentration were observed and analysis of these data revealed that the chiral recognition occurs in the step of liberation of p-nitrophenol by intra-complex thiolysis, not in the complex-forming step.A possible mechanism for the anantioselectivity is proposed on the basis of the kinetic data.Keywords - crown ether; transacylation; pseudo-first-order rate constant; enantioselectivity; thiolysis; intra-complex reaction; enzyme model
Asymmetric Induction in Diels-Alder Reactions to Acrylates Derived from Chiral sec-Alcohols
Oppolzer, Wolfgang,Kurth, Mark,Reichlin, Daniel,Chapuis, Christian,Mohnhaupt, Martin,Moffatt, Frank
, p. 2802 - 2807 (2007/10/02)
Starting from the enantiomerically pure monoterpenes (+)-pulegone (3), (+)-limonene (7), (-)-β-pinene (9), (+)- and (-)-camphor (13) or (+)-cholestenone (11) the chiral alcohols 4, 5, 6, 8, 10, 12, 14, 15, 16, 17 and 18 were prepared; their acrylates II underwent a TiCl4-promoted Diels-Alder addition to cyclopentadiene (Scheme 3, Table) giving in a predictable manner either the (2R)- or the (2S)-adducts III with 63 to 88percent asymmetric induction.