Glycosylation Reactions with a (4-Alkoxypentadienyl)oxy Leaving Group Linking the Glycosyl Donor and the Acceptor Moiety

1999 ◽  
Vol 64 (4) ◽  
pp. 1319-1325 ◽  
Author(s):  
Götz Scheffler ◽  
Richard R. Schmidt
Keyword(s):  
Leaving Group ◽  
Glycosyl Donor ◽  
Acceptor Moiety

scholarly journals Intramolecular glycosylation

2017 ◽  
Vol 13 ◽  
pp. 2028-2048 ◽  
Author(s):  
Xiao G Jia ◽  
Alexei V Demchenko
Keyword(s):  
Review Article ◽  
Donor And Acceptor ◽  
Leaving Group ◽  
Glycosyl Donor

Carbohydrate oligomers remain challenging targets for chemists due to the requirement for elaborate protecting and leaving group manipulations, functionalization, tedious purification, and sophisticated characterization. Achieving high stereocontrol in glycosylation reactions is arguably the major hurdle that chemists experience. This review article overviews methods for intramolecular glycosylation reactions wherein the facial stereoselectivity is achieved by tethering of the glycosyl donor and acceptor counterparts.

scholarly journals Hydrolysis of Glycosyl Thioimidates by Glycoside Hydrolase Requires Remote Activation for Efficient Activity

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 826 ◽  
Author(s):  
Guillotin ◽  
Assaf ◽  
Pistorio ◽  
Lafite ◽  
Demchenko ◽  
...  
Keyword(s):  
Enzymatic Hydrolysis ◽  
Active Site ◽  
In Silico ◽  
Glycoside Hydrolase ◽  
Chemoenzymatic Synthesis ◽  
Leaving Group ◽  
Glycosyl Donor ◽  
In Silico Modelling ◽  
Leaving Group Ability ◽  
Hydrolysis Of

Chemoenzymatic synthesis of glycosides relies on efficient glycosyl donor substrates able to react rapidly and efficiently, yet with increased stability towards chemical or enzymatic hydrolysis. In this context, glycosyl thioimidates have previously been used as efficient donors, in the case of hydrolysis or thioglycoligation. In both cases, the release of the thioimidoyl aglycone was remotely activated through a protonation driven by a carboxylic residue in the active site of the corresponding enzymes. A recombinant glucosidase (DtGly) from Dictyoglomus themophilum, previously used in biocatalysis, was also able to use such glycosyl thioimidates as substrates. Yet, enzymatic kinetic values analysis, coupled to mutagenesis and in silico modelling of DtGly/substrate complexes demonstrated that the release of the thioimidoyl moiety during catalysis is only driven by its leaving group ability, without the activation of a remote protonation. In the search of efficient glycosyl donors, glycosyl thioimidates are attractive and efficient. Their utility, however, is limited to enzymes able to promote leaving group release by remote activation.

scholarly journals Matching Glycosyl Donor Reactivity to Sulfonate Leaving Group Ability Permits SN2 Glycosylations

2019 ◽  
Vol 141 (42) ◽  
pp. 16743-16754 ◽  
Author(s):  
Ming-Hua Zhuo ◽  
David J. Wilbur ◽  
Eugene E. Kwan ◽  
Clay S. Bennett
Keyword(s):  
Leaving Group ◽  
Glycosyl Donor ◽  
Leaving Group Ability

General Cyclopropane Assembly via Enantioselective Redox-Active Carbene Transfer to Aliphatic Olefins

2018 ◽  
Author(s):  
Marc Montesinos-Magraner ◽  
Matteo Costantini ◽  
Rodrigo Ramirez-Contreras ◽  
Michael E. Muratore ◽  
Magnus J. Johansson ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Asymmetric Synthesis ◽  
Chemical Space ◽  
Synthetic Approach ◽  
Asymmetric Cyclopropanation ◽  
Redox Active ◽  
Wide Range ◽  
Leaving Group ◽  
Stereoelectronic Properties ◽  
Carbene Transfer

Asymmetric cyclopropane synthesis currently requires bespoke strategies, methods, substrates and reagents, even when targeting similar compounds. This limits the speed and chemical space available for discovery campaigns. Here we introduce a practical and versatile diazocompound, and we demonstrate its performance in the first unified asymmetric synthesis of functionalized cyclopropanes. We found that the redox-active leaving group in this reagent enhances the reactivity and selectivity of geminal carbene transfer. This effect enabled the asymmetric cyclopropanation of a wide range of olefins including unactivated aliphatic alkenes, enabling the 3-step total synthesis of (–)-dictyopterene A. This unified synthetic approach delivers high enantioselectivities that are independent of the stereoelectronic properties of the functional groups transferred. Our results demonstrate that orthogonally-differentiated diazocompounds are viable and advantageous equivalents of single-carbon chirons<i>.</i>

Allylic Amination via Acid Catalyzed Leaving Group Activation

2016 ◽  
Vol 3 (2) ◽  
pp. 145-159
Author(s):  
Marija Skvorcova ◽  
Aigars Jirgensons
Keyword(s):  
Allylic Amination ◽  
Leaving Group ◽  
Acid Catalyzed
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