scholarly journals Glycosylation reactions mediated by hypervalent iodine: application to the synthesis of nucleosides and carbohydrates

2018 ◽  
Vol 14 ◽  
pp. 1595-1618 ◽  
Author(s):  
Yuichi Yoshimura ◽  
Hideaki Wakamatsu ◽  
Yoshihiro Natori ◽  
Yukako Saito ◽  
Noriaki Minakawa
Keyword(s):  
Lewis Acid ◽  
Acid Catalyst ◽  
Hypervalent Iodine ◽  
Carbocyclic Nucleosides ◽  
Coupling Reactions ◽  
Glycoside Bond ◽  
Lewis Acid Catalyst ◽  
Glycosylation Reaction

To synthesize nucleoside and oligosaccharide derivatives, we often use a glycosylation reaction to form a glycoside bond. Coupling reactions between a nucleobase and a sugar donor in the former case, and the reaction between an acceptor and a sugar donor of in the latter are carried out in the presence of an appropriate activator. As an activator of the glycosylation, a combination of a Lewis acid catalyst and a hypervalent iodine was developed for synthesizing 4’-thionucleosides, which could be applied for the synthesis of 4’-selenonucleosides as well. The extension of hypervalent iodine-mediated glycosylation allowed us to couple a nucleobase with cyclic allylsilanes and glycal derivatives to yield carbocyclic nucleosides and 2’,3’-unsaturated nucleosides, respectively. In addition, the combination of hypervalent iodine and Lewis acid could be used for the glycosylation of glycals and thioglycosides to produce disaccharides. In this paper, we review the use of hypervalent iodine-mediated glycosylation reactions for the synthesis of nucleosides and oligosaccharide derivatives.

Computationally-Guided Investigation of Dual Amine/pi Lewis Acid Catalysts for Direct Additions of Aldehydes and Ketones to Unactivated Alkenes and Alkynes

2020 ◽  
Author(s):  
Eric Greve ◽  
Jacob D. Porter ◽  
Chris Dockendorff
Keyword(s):  
Lewis Acid ◽  
Density Functional ◽  
Acid Catalyst ◽  
Metal Catalyst ◽  
Catalyst Poisoning ◽  
Lewis Acid Catalysts ◽  
Metal Ligands ◽  
Aldehydes And Ketones ◽  
Lewis Acid Catalyst ◽  
Catalyst Systems

Dual amine/pi Lewis acid catalyst systems have been reported for intramolecular direct additions of aldehydes/ketones to unactivated alkynes and occasionally alkenes, but related intermolecular reactions are rare and not presently of significant synthetic utility, likely due to undesired coordination of enamine intermediates to the metal catalyst. We reasoned that bulky metal ligands and bulky amine catalysts could minimize catalyst poisoning and could facilitate certain examples of direct intermolecular additions of aldehyde/ketones to alkenes/alkynes. Density Functional Theory (DFT) calculations were performed that suggested that PyBOX-Pt(II) catalysts for alkene/alkyne activation could be combined with MacMillan’s imidazolidinone organocatalyst for aldehyde/ketone activation to facilitate desirable C-C bond formations, and certain reactions were calculated to be more exergonic than catalyst poisoning pathways. As calculated, preformed enamines generated from the MacMillan imidazolidinone did not displace ethylene from a biscationic (<i>t</i>-Bu)PyBOX-Pt<sup>2+</sup>complex, but neither were the desired C-C bond formations observed under several different conditions.

Computationally-Guided Investigation of Dual Amine/pi Lewis Acid Catalysts for Direct Additions of Aldehydes and Ketones to Unactivated Alkenes and Alkynes

2020 ◽  
Author(s):  
Eric Greve ◽  
Jacob D. Porter ◽  
Chris Dockendorff
Keyword(s):  
Lewis Acid ◽  
Density Functional ◽  
Acid Catalyst ◽  
Metal Catalyst ◽  
Catalyst Poisoning ◽  
Lewis Acid Catalysts ◽  
Metal Ligands ◽  
Aldehydes And Ketones ◽  
Lewis Acid Catalyst ◽  
Catalyst Systems

Dual amine/pi Lewis acid catalyst systems have been reported for intramolecular direct additions of aldehydes/ketones to unactivated alkynes and occasionally alkenes, but related intermolecular reactions are rare and not presently of significant synthetic utility, likely due to undesired coordination of enamine intermediates to the metal catalyst. We reasoned that bulky metal ligands and bulky amine catalysts could minimize catalyst poisoning and could facilitate certain examples of direct intermolecular additions of aldehyde/ketones to alkenes/alkynes. Density Functional Theory (DFT) calculations were performed that suggested that PyBOX-Pt(II) catalysts for alkene/alkyne activation could be combined with MacMillan’s imidazolidinone organocatalyst for aldehyde/ketone activation to facilitate desirable C-C bond formations, and certain reactions were calculated to be more exergonic than catalyst poisoning pathways. As calculated, preformed enamines generated from the MacMillan imidazolidinone did not displace ethylene from a biscationic (<i>t</i>-Bu)PyBOX-Pt<sup>2+</sup>complex, but neither were the desired C-C bond formations observed under several different conditions.

Bis(pentafluorophenyl)tin Dibromide as a Novel Organotin Halide Lewis Acid Catalyst

Synlett ◽  
1996 ◽  
Vol 1996 (09) ◽  
pp. 877-879 ◽  
Author(s):  
Jianxie Chen ◽  
Katsumasa Sakamoto ◽  
Akihiro Orita ◽  
Junzo Otera
Keyword(s):  
Lewis Acid ◽  
Acid Catalyst ◽  
Lewis Acid Catalyst

Asymmetric synthesis of isoquinuclidines by Diels–Alder reaction of 1,2-dihydropyridine utilizing a chiral Lewis acid catalyst

Tetrahedron ◽  
2012 ◽  
Vol 68 (6) ◽  
pp. 1774-1781 ◽  
Author(s):  
Chigusa Seki ◽  
Masafumi Hirama ◽  
N.D.M. Romauli Hutabarat ◽  
Junko Takada ◽  
Chonticha Suttibut ◽  
...  
Keyword(s):  
Asymmetric Synthesis ◽  
Lewis Acid ◽  
Acid Catalyst ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
Chiral Lewis Acid ◽  
Lewis Acid Catalyst

ZrOCl2·8H2O: an efficient Lewis acid catalyst for the one-pot multicomponent synthesis of β-acetamido ketones

Tetrahedron ◽  
2006 ◽  
Vol 62 (17) ◽  
pp. 4059-4064 ◽  
Author(s):  
Rina Ghosh ◽  
Swarupananda Maiti ◽  
Arijit Chakraborty ◽  
Santu Chakraborty ◽  
Alok K. Mukherjee
Keyword(s):  
Lewis Acid ◽  
Acid Catalyst ◽  
Multicomponent Synthesis ◽  
One Pot ◽  
Lewis Acid Catalyst ◽  
The One
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