Catalyst-Controlled Regiodivergent Synthesis of 1- and 3-Thiosugars with High Stereoselectivity and Chemoselectivity

ACS Catalysis ◽  
2021 ◽  
pp. 5287-5293
Author(s):  
Yuexin Liu ◽  
Yang Jiao ◽  
Huajun Luo ◽  
Nianyu Huang ◽  
Mengnan Lai ◽  
...  
Keyword(s):  
High Stereoselectivity

scholarly journals Broad scope gold(i)-catalysed polyenyne cyclisations for the formation of up to four carbon–carbon bonds

2017 ◽  
Vol 15 (10) ◽  
pp. 2163-2167 ◽  
Author(s):  
Zhouting Rong ◽  
Antonio M. Echavarren
Keyword(s):  
Single Step ◽  
Simultaneous Formation ◽  
Broad Scope ◽  
Carbon Carbon Bonds ◽  
Carbon Bonds ◽  
First Time ◽  
High Stereoselectivity

The polycyclisation of polyeneynes catalyzed by gold(i) has been extended for the first time to the simultaneous formation of up to four carbon–carbon bonds, leading to steroid-like molecules with high stereoselectivity in a single step with low catalyst loadings.

scholarly journals ω-Amino Acid:Pyruvate Transaminase from Alcaligenes denitrificans Y2k-2: a New Catalyst for Kinetic Resolution of β-Amino Acids and Amines

2004 ◽  
Vol 70 (4) ◽  
pp. 2529-2534 ◽  
Author(s):  
Hyungdon Yun ◽  
Seongyop Lim ◽  
Byung-Kwan Cho ◽  
Byung-Gee Kim
Keyword(s):  
Amino Acids ◽  
Kinetic Resolution ◽  
Specific Activity ◽  
Expression System ◽  
Enantiomeric Excess ◽  
Selective Enrichment ◽  
Alcaligenes Denitrificans ◽  
Keto Acids ◽  
Optically Pure ◽  
High Stereoselectivity

ABSTRACT Alcaligenes denitrificans Y2k-2 was obtained by selective enrichment followed by screening from soil samples, which showed ω-amino acid:pyruvate transaminase activity, to kinetically resolve aliphatic β-amino acid, and the corresponding structural gene (aptA) was cloned. The gene was functionally expressed in Escherichia coli BL21 by using an isopropyl-β-d-thiogalactopyranoside (IPTG)-inducible pET expression system (9.6 U/mg), and the recombinant AptA was purified to show a specific activity of 77.2 U/mg for l-β-amino-n-butyric acid (l-β-ABA). The enzyme converts various β-amino acids and amines to the corresponding β-keto acids and ketones by using pyruvate as an amine acceptor. The apparent Km and V max for l-β-ABA were 56 mM and 500 U/mg, respectively, in the presence of 10 mM pyruvate. In the presence of 10 mM l-β-ABA, the apparent Km and V max for pyruvate were 11 mM and 370 U/mg, respectively. The enzyme exhibits high stereoselectivity (E > 80) in the kinetic resolution of 50 mM d,l-β-ABA, producing optically pure d-β-ABA (99% enantiomeric excess) with 53% conversion.

Copper-Catalyzed Oxidative Self-Coupling of α-Amino Carbonyl Compounds for the Synthesis of Tetrasubstituted 1,4-Enediones

Synlett ◽  
2018 ◽  
Vol 29 (18) ◽  
pp. 2422-2426
Author(s):  
Bing Yi ◽  
Jiannan Xiang ◽  
Niannian Yi ◽  
Yi Xiong ◽  
Qingjun Huang ◽  
...  
Keyword(s):  
Double Bond ◽  
Carbonyl Compound ◽  
Carbonyl Compounds ◽  
Simultaneous Formation ◽  
High Stereoselectivity

A protocol for the copper-catalyzed oxidative self-coupling of α-amino carbonyl compounds has been developed for the synthesis of tetrasubstituted 1,4-enediones (Z-isomers) in moderate to good yields through the cleavage of four sp3C–H bonds and the simultaneous formation of one C=C double bond in the α-amino carbonyl compound. The strategy has the advantages of using readily available starting ­materials and of high stereoselectivity.

scholarly journals Solid state catalytic hydrogen exchange for deuterium in cycloprolylglycine

2019 ◽  
Vol 484 (3) ◽  
pp. 307-311
Author(s):  
A. K. Dadayan ◽  
Yu. A. Borisov ◽  
E. V. Bocharov ◽  
Yu. A. Zolotarev ◽  
I. Yu. Nagaev ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Solid State ◽  
Hydrogen Isotope ◽  
Isotope Exchange ◽  
Density Functional ◽  
Hydrogen Exchange ◽  
Functional Theory ◽  
Catalytic Hydrogen ◽  
Spillover Hydrogen ◽  
High Stereoselectivity

The reaction of spillover hydrogen (SH) with cyclopropylglycine (cPG) in high-temperature solid-state catalytic hydrogen isotope exchange (HTCIE) has been studied experimentally and using density functional theory (DFT). NMR spectroscopy and mass spectrometry have shown a high regioselectivity and stereoselectivity for the reaction of spillover hydrogen with cPG fragments. The Gly fragment has been shown to be the most reactive in HTCIE, for which high stereoselectivity of substitution of hydrogen by deuterium has been demonstrated.

Bifunctional squaramide catalyzed stereoselective Mannich reaction of α-azido ketones with isatin-derived ketimines

2020 ◽  
Vol 18 (3) ◽  
pp. 479-487 ◽  
Author(s):  
Seda Karahan ◽  
Cihangir Tanyeli
Keyword(s):  
Mannich Reaction ◽  
Optically Active ◽  
First Time ◽  
High Stereoselectivity

Bifunctional squaramide catalyzed asymmetric Mannich reaction of alpha-azido ketones and isatin derived ketiminines were established for the first time with high stereoselectivity. Adducts are valuable synthons for optically active heterocycles.

Copper-Catalyzed Direct α-Nitration of Nitrostilbenes with Nitrogen Dioxide

Synlett ◽  
2019 ◽  
Vol 30 (07) ◽  
pp. 833-836
Author(s):  
Kai Chen ◽  
Xi Gao ◽  
Hui Zou ◽  
Guan Xiao ◽  
Xin Peng
Keyword(s):  
Nitrogen Dioxide ◽  
Efficient Method ◽  
High Stereoselectivity

A novel and efficient method for the direct α-nitration of nitrostilbenes was developed in which NO2 was used as the nitro source. This method provided (E)-α-nitrostilbenes derivatives in moderate to good yields. A broad substrate scope, mild and convenient conditions, and high stereoselectivity are important features of this method.

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