111138-43-3Relevant articles and documents
Enzymatic Access to Homochiral 1-Acetoxy-2-hydroxycyclohexane-3,5-diene through Lipase-assisted Acetylation in Organic Solvent
Nicolosi, Giovanni,Patti, Angela,Piattelli, Mario,Sanfilippo, Claudia
, p. 6545 - 6546 (1995)
Enantiotoposelective acetylation of cis-1,2-dihydroxycyclohexa-3,5-diene with vinyl acetate in tert-butyl methyl ether, promoted by immobilized lipase from Mucor miehei (Lipozyme IM), afforded (1R,2S)-1-acetoxy-2-hydroxycyclohexa-3,5-diene in good chemical yield and high enantiomeric excess.
Uncovering Key Structural Features of an Enantioselective Peptide-Catalyzed Acylation Utilizing Advanced NMR Techniques
Procházková, Eli?ka,Kolmer, Andreas,Ilgen, Julian,Schwab, Mira,Kaltschnee, Lukas,Fredersdorf, Maic,Schmidts, Volker,Wende, Raffael C.,Schreiner, Peter R.,Thiele, Christina M.
, p. 15754 - 15759 (2016/12/16)
We report on a detailed NMR spectroscopic study of the catalyst-substrate interaction of a highly enantioselective oligopeptide catalyst that is used for the kinetic resolution of trans-cycloalkane-1,2-diols via monoacylation. The extraordinary selectivity has been rationalized by molecular dynamics as well as density functional theory (DFT) computations. Herein we describe the conformational analysis of the organocatalyst studied by a combination of nuclear Overhauser effect (NOE) and residual dipolar coupling (RDC)-based methods that resulted in an ensemble of four final conformers. To corroborate the proposed mechanism, we also investigated the catalyst in mixtures with both trans-cyclohexane-1,2-diol enantiomers separately, using advanced NMR methods such as T1relaxation time and diffusion-ordered spectroscopy (DOSY) measurements to probe molecular aggregation. We determined intramolecular distance changes within the catalyst after diol addition from quantitative NOE data. Finally, we developed a pure shift EASY ROESY experiment using PSYCHE homodecoupling to directly observe intermolecular NOE contacts between the trans-1,2-diol and the cyclohexyl moiety of the catalyst hidden by spectral overlap in conventional spectra. All experimental NMR data support the results proposed by earlier computations including the proposed key role of dispersion interaction.
A photoinduced cyclization cascade - Total synthesis of (-)-leuconoxine
Pfaffenbach, Magnus,Gaich, Tanja
, p. 6355 - 6357 (2015/04/22)
A protecting-group-free and enantioselective total synthesis of the monoterpenoid indole alkaloid (-)-leuconoxine was accomplished. The key step comprises a novel photoinduced domino macrocyclization/transannular cyclization involving the Witkop cyclization, for which additional mechanistic evidence is provided. This process furnishes a diaza[5.5.6.6]fenestrane skeleton, which is a hitherto unprecedented structure element.
Highly enantioselective organocatalytic oxidative kinetic resolution of secondary alcohols using chiral alkoxyamines as precatalysts: Catalyst structure, active species, and substrate scope
Murakami, Keiichi,Sasano, Yusuke,Tomizawa, Masaki,Shibuya, Masatoshi,Kwon, Eunsang,Iwabuchi, Yoshiharu
supporting information, p. 17591 - 17600 (2015/02/19)
The development and characterization of enantioselective organocatalytic oxidative kinetic resolution (OKR) of racemic secondary alcohols using chiral alkoxyamines as precatalysts are described. A number of chiral alkoxyamines have been synthesized, and their structure-enantioselectivity correlation study in OKR has led us to identify a promising precatalyst, namely, 7-benzyl-3-n-butyl-4-oxa-5-azahomoadamantane, which affords various chiral aliphatic secondary alcohols (ee up to >99%, krel up to 296). In a mechanistic study, chlorine-containing oxoammonium species were identified as the active species generated in situ from the alkoxyamine precatalyst, and it was revealed that the chlorine atom is crucial for high reactivity and enantioselectivity. The present OKR is the first successful example applicable to various unactivated aliphatic secondary alcohols, including heterocyclic alcohols with high enantioselectivity, the synthetic application of which is demonstrated by the synthesis of a bioactive compound.
