Asymmetric hydrolysis of enol esters with two esterases from Marchantia polymorpha
摘要:
Two esterases participating in the asymmetric hydrolysis of a-alkylated enol acetates to a-chiral ketones were isolated from the cultured cells of Marchantia polymorpha. These two esterases had opposite enantioselectivities and both of them reversed the stereoselectivity of protonation into the enol intermediate in the hydrolysis when the chain length and the bulkiness of a-substituents were increased. (C) 2000 Elsevier Science Ltd. All rights reserved.
Like an enzyme: Asymmetric hydrolysis of enolesters is accomplished by chiral phase‐transfer catalysts under biphasic base hydrolysis conditions. Stoichiometric reactions support the generation of a well‐organized chiral ammonium hydroxide species (Q+OH−).
α-Nitro Ketones; 8<sup>1</sup>. Nitration of Enol Acetates with Trifluoroacetic Anhydride and Ammonium Nitrate
作者:Pimchit Dampawan、Walter W. Zajac, Jr.
DOI:10.1055/s-1983-30417
日期:——
Enantioface-differentiating protonation with chiral γ-hydroxyselenoxides
作者:Tamiko Takahashi、Naoki Nakao、Toru Koizumi
DOI:10.1016/s0957-4166(97)00423-0
日期:1997.10
Enantioface-differentiating protonation of achiral metal enolates of alpha-alkylcarbonyl compounds 7 has been developed using chiral gamma-hydroxyselenoxides 1 as a proton source. Reaction of zinc bromide enolates of 2-benzyl- and 2-n-propylcyclohexanones with (S-se)-1e gave (S)-2-benzylcyclohexanone 7a and (R)-2-n-propylcyclohexanone 7e in high enantiomeric excess, respectively. Intramolecular hydrogen bonding of the selenoxide 1, chelation effects between 1 and metal enolate, and 2-exo-hydroxy-10-bornyl-framework could contribute to this asymmetric induction. (C) 1997 Elsevier Science. Ltd.
MATSUMOTO, KAZUTSUGU;TSUTSUMI, SEIJI;IHORI, TAMIKO;OHTA, HIROMICHI, J. AMER. CHEM. SOC., 112,(1990) N6, C. 9614-9619