Kinetic resolution of 2,2-disubstituted-1,3-diketones via carbene catalysis

2019 ◽  
Vol 6 (3) ◽  
pp. 290-298 ◽  
Author(s):  
Weici Xu ◽  
Yuanzhen Li ◽  
Rui Liu ◽  
Shuang Yang ◽  
Jian Liu ◽  
...  
Keyword(s):  
Kinetic Resolution ◽  
Quaternary Stereocenters ◽  
First Time

Organocatalytic kinetic resolution of 1,3-diketones with central quaternary stereocenters was achieved for the first time. The resolution proceeds via two basic modes, and the inherent principles between the different combinations of ketone groups and the resolution patterns were also disclosed.

scholarly journals Enantioselective Transesterification of Allyl Alcohols with (E)-4-Arylbut-3-en-2-ol Motif by Immobilized Lecitase™ Ultra

Catalysts ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 798
Author(s):  
Aleksandra Leśniarek ◽  
Anna Chojnacka ◽  
Radosław Drozd ◽  
Magdalena Szymańska ◽  
Witold Gładkowski
Keyword(s):  
High Activity ◽  
Cyanogen Bromide ◽  
Kinetic Resolution ◽  
Negative Effects ◽  
Subsequent Reaction ◽  
Wide Range ◽  
Allyl Alcohols ◽  
Reaction Cycles ◽  
Acyl Donors ◽  
First Time

Lecitase™ Ultra was immobilized on four different supports and tested for the first time as the biocatalyst in the kinetic resolution of racemic allyl alcohols with the (E)-4-arylbut-3-en-2-ol system in the process of transesterification. The most effective biocatalyst turned out to be the enzyme immobilized on agarose activated with cyanogen bromide (LU-CNBr). The best results (E > 200, ees and eep = 95–99%) were obtained for (E)-4-phenylbut-3-en-2-ol and its analog with a 2,5-dimethylphenyl ring whereas the lowest ee of kinetic resolution products (90%) was achieved for the substrate with a 4-methoxyphenyl substituent. For all substrates, (R)-enantiomers were esterified faster than their (S)-antipodes. The results showed that LU-CNBr is a versatile biocatalyst, showing high activity and enantioselectivity in a wide range of organic solvents in the presence of commonly used acyl donors. High operational stability of LU-CNBr allows it to be reused in three subsequent reaction cycles without negative effects on the efficiency and enantioselectivity of transesterification. This biocatalyst can become attractive to the commercial lipases in the process of the kinetic resolution of allyl alcohols.

scholarly journals Stereospecific, Ligand-Free Synthesis of All-Carbon Quaternary Stereocenters from Tertiary Benzylic Carboxylates

2021 ◽  
Author(s):  
Jianyu Xu ◽  
Sarah Pound ◽  
Corey Basch ◽  
Alana Duke ◽  
Mary Watson
Keyword(s):  
The Past ◽  
Ligand Free ◽  
Quaternary Stereocenters ◽  
High Yields ◽  
First Time

Nickel-catalyzed, stereospecific cross-couplings via activation of secondary C–O bonds has been well developed in the past few years. Meanwhile, stereospecific cross-couplings of tertiary electrophiles have been rarely explored. Herein, we describe a nickel-catalyzed, ligand-free Suzuki-Miyaura vinylation, using easily prepared, highly enantioenriched tertiary benzylic carboxylates to install all-carbon quaternary stereocenters in high yields and ee’s. In addition to allowing stereospecific vinylation of these substrates for the first time, this method overcomes the longstanding requirement for a naphthyl group on the benzylic carboxylate<br>

Kinetic resolution of β-ketoesters with quaternary stereocenters via a carbene-catalyzed benzoin reaction

2019 ◽  
Vol 17 (8) ◽  
pp. 2169-2173 ◽  
Author(s):  
Syeda Tazeen Zehra ◽  
Guoxiang Zhang ◽  
Shuang Yang ◽  
Xinqiang Fang
Keyword(s):  
Kinetic Resolution ◽  
Quaternary Stereocenters

N-Heterocyclic carbene-catalyzed kinetic resolution is used to produce enantioenriched β-ketoesters with quaternary stereocenters. Sterically bulky substituents such as benzyl, allyl, phenyl and cyclopropyl groups are all tolerated in this method.

Studies of Australian Soft Corals. XLIII. The Structure Elucidation of a New Diterpene From Alcyonium molle

1989 ◽  
Vol 42 (5) ◽  
pp. 665 ◽  
Author(s):  
BF Bowden ◽  
JC Coll ◽  
MC Dai
Keyword(s):  
Absolute Configuration ◽  
High Field ◽  
Structure Elucidation ◽  
Kinetic Resolution ◽  
Soft Coral ◽  
Soft Corals ◽  
Resolution Method ◽  
The Absolute ◽  
First Time

The isolation of a new cladiellin based diterpene (6), (1S,2R,3S,4R,SR,6S,8E,11S,12R,13S,14S)-3-acetoxy-2,12-dibutanoyloxycladiell-8-ene-4,11-diol is reported from the soft coral Alcyonium molle (Octocorallia, Alcyonacea, Alcyoniidae). The structure was deduced by high-field n.m.r. spectroscopy including 13C-lH shift correlated 2D n.m.r. experiments and n.O.e. measurements. The absolute configuration was based on the kinetic resolution method of Horeau. This highly derivatized diterpene (6) is the first alcyonacean derived metabolite to possess hydroxy functionalities protected as butyrate esters, although this feature is relatively common among gorgonacean metabolites. Gorgosterol (7), which cooccurs with (6) in A. molle was identified and its 13C n.m.r. spectrum reported for the first time.

Dynamic kinetic resolution of bis-aryl succinic anhydrides: enantioselective synthesis of densely functionalised γ-butyrolactones

2018 ◽  
Vol 54 (26) ◽  
pp. 3231-3234 ◽  
Author(s):  
Romain Claveau ◽  
Brendan Twamley ◽  
Stephen J. Connon
Keyword(s):  
Kinetic Resolution ◽  
Enantioselective Synthesis ◽  
Dynamic Kinetic Resolution ◽  
First Time

The efficient Dynamic Kinetic Resolution (DKR) of disubstituted anhydrides has been shown to be possible for the first time.

Catalytic asymmetric oxidative carbonylation-induced kinetic resolution of sterically hindered benzylamines to chiral isoindolinones

2021 ◽  
Vol 57 (14) ◽  
pp. 1778-1781
Author(s):  
Qiu-Qi Mu ◽  
Yi-Xue Nie ◽  
Hang Li ◽  
Xing-Feng Bai ◽  
Xue-Wei Liu ◽  
...  
Keyword(s):  
Transition Metal ◽  
Kinetic Resolution ◽  
Oxidative Carbonylation ◽  
Sterically Hindered ◽  
Transition Metal Catalyzed ◽  
Catalytic Asymmetric ◽  
Metal Catalyzed ◽  
First Time

A highly enantioselective kinetic resolution of sterically hindered benzylamines has been achieved for the first time through transition-metal-catalyzed oxidative carbonylation.

scholarly journals Enantioselective Synthesis of Cyclic Nitrones and Oxime Ethers by Chemoselective Allylic Alkylation of Oximes

2020 ◽  
Author(s):  
Tobias Sandmeier ◽  
Erick Carreira
Keyword(s):  
Kinetic Resolution ◽  
Cycloaddition Reaction ◽  
Marine Natural Product ◽  
Allylic Alcohols ◽  
Allylic Alkylation ◽  
Reaction Conditions ◽  
Cyclic Nitrones ◽  
First Time ◽  
Reaction Cascades ◽  
Isomeric Mixtures

The enantio- and chemoselective iridium-catalyzed <i>N</i>- and<i> O</i>-allylation of oximes is described for the first time. Kinetic resolution in an intramolecular setting provides access to cyclic nitrones, oxime ethers and enantioenriched aliphatic allylic alcohols. Salient features of this transformation are its ability to employ <i>E</i>/<i>Z</i>-isomeric mixtures of oxime starting materials convergently, high functional group tolerance, and divergent <i>N</i>- or <i>O</i>-allylation by choice of the reaction conditions. The implementation of <i>N</i>-allylation/1,3-dipolar cycloaddition reaction cascades furnish tricyclic isoxazolidines in highly enantio- and diastereoselective fashion. Expansion of this approach to the selective allylation of hydrazones allows enantioselective preparation of azomethine imines. The synthetic utility of the approach is demonstrated by the efficient, formal syntheses of glycoprotein GP IIb‐IIIa receptor antagonist (–)-roxifiban and marine natural product (+)-halichlorine.

scholarly journals Enantioselective Synthesis of Cyclic Nitrones and Oxime Ethers by Chemoselective Allylic Alkylation of Oximes

2020 ◽  
Author(s):  
Tobias Sandmeier ◽  
Erick Carreira
Keyword(s):  
Kinetic Resolution ◽  
Cycloaddition Reaction ◽  
Marine Natural Product ◽  
Allylic Alcohols ◽  
Allylic Alkylation ◽  
Reaction Conditions ◽  
Cyclic Nitrones ◽  
First Time ◽  
Reaction Cascades ◽  
Isomeric Mixtures

The enantio- and chemoselective iridium-catalyzed <i>N</i>- and<i> O</i>-allylation of oximes is described for the first time. Kinetic resolution in an intramolecular setting provides access to cyclic nitrones, oxime ethers and enantioenriched aliphatic allylic alcohols. Salient features of this transformation are its ability to employ <i>E</i>/<i>Z</i>-isomeric mixtures of oxime starting materials convergently, high functional group tolerance, and divergent <i>N</i>- or <i>O</i>-allylation by choice of the reaction conditions. The implementation of <i>N</i>-allylation/1,3-dipolar cycloaddition reaction cascades furnish tricyclic isoxazolidines in highly enantio- and diastereoselective fashion. Expansion of this approach to the selective allylation of hydrazones allows enantioselective preparation of azomethine imines. The synthetic utility of the approach is demonstrated by the efficient, formal syntheses of glycoprotein GP IIb‐IIIa receptor antagonist (–)-roxifiban and marine natural product (+)-halichlorine.

ChemInform Abstract: Enantioselective Formation of Cyano-Bearing All-Carbon Quaternary Stereocenters: Copper-Catalyzed N-Arylation via Kinetic Resolution.

ChemInform ◽  
2016 ◽  
Vol 47 (6) ◽  
pp. no-no
Author(s):  
Yan Long ◽  
Jialing Shi ◽  
Haoqiang Liang ◽  
Youlin Zeng ◽  
Qian Cai
Keyword(s):  
Kinetic Resolution ◽  
Quaternary Stereocenters

scholarly journals Organocatalytic asymmetric Henry reaction of 1H-pyrrole-2,3-diones with bifunctional amine-thiourea catalysts bearing multiple hydrogen-bond donors

2016 ◽  
Vol 12 ◽  
pp. 295-300 ◽  
Author(s):  
Ming-Liang Zhang ◽  
Deng-Feng Yue ◽  
Zhen-Hua Wang ◽  
Yuan Luo ◽  
Xiao-Ying Xu ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Henry Reaction ◽  
Multiple Hydrogen Bond ◽  
Catalytic Asymmetric ◽  
Quaternary Stereocenters ◽  
First Time ◽  
Hydrogen Bond Donors

For the first time, a catalytic asymmetric Henry reaction of 1H-pyrrole-2,3-diones was achieved with a chiral bifunctional amine-thiourea as a catalyst possessing multiple hydrogen-bond donors. With this developed method, a range of 3-hydroxy-3-nitromethyl-1H-pyrrol-2(3H)-ones bearing quaternary stereocenters were obtained in acceptable yield (up to 75%) and enantioselectivity (up to 73% ee).

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