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ChemComm Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: S. Medina, A. Henderson, J. Bower and M. C. Galan, Chem. Commun., 2015, DOI: 10.1039/C5CC02552D.
This is an Accepted Manuscript, which has been through the Royal Society of Chemistry peer review process and has been accepted for publication. Accepted Manuscripts are published online shortly after acceptance, before technical editing, formatting and proof reading. Using this free service, authors can make their results available to the community, in citable form, before we publish the edited article. We will replace this Accepted Manuscript with the edited and formatted Advance Article as soon as it is available. You can find more information about Accepted Manuscripts in the Information for Authors. Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal’s standard Terms & Conditions and the Ethical guidelines still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains.
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Journal Name
ChemComm
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DOI: 10.1039/C5CC02552D
Cite this: DOI: 10.1039/c0xx00000x
ARTICLE TYPE
www.rsc.org/xxxxxx
Stereoselective synthesis of glycosides using (salen)Co catalysts as promoters.
5
10
Received (in XXX, XXX) Xth XXXXXXXXX 20XX, Accepted Xth XXXXXXXXX 20XX DOI: 10.1039/b000000x The use of (salen)Co catalysts as a new class of bench-stable stereoselective glycosylation promoters of trichloroacetimidate glycosyl donors at room temperature is described. The conditions are practical and do not require the use of molecular sieves with products being isolated in good to high yields.
35
40
15
20
Access to structurally defined oligosaccharides in sufficient amounts to be used as probes for biological research, still represents a significant challenge due to the structural complexity of carbohydrates. The stereoselective coupling of glycosides is often considered the main bottleneck towards this goal and despite significant efforts devoted to the development of efficient glycosylation strategies, there is still a need for robust and practical methods to achieve this crucial step.1 Transition metal catalysis applied to oligosaccharide synthesis offers great promise at achieving high yields and anomeric selectivities by the careful choice of the metal and ligands attached to the metal centre.2
Table 1. Reaction optimization of trichloroacetimidate 3 with model acceptor 4a.
Entry
25
30
This journal is © The Royal Society of Chemistry [year]
Catalyst
Solvent
T (h)
Yield (%)
[a] α:β
1
1a
CH2Cl2
24
n/o
n/o
2
1b
CH2Cl2
22
89
1:1.5
3
1c
CH2Cl2
0.5
74
1.3:1
4
2a
CH2Cl2
24
64
1:2.6
5
2b
CH2Cl2
24
n/o
n/o
6
2c
CH2Cl2
22
70
1:2.6
7
2d
CH2Cl2
0.5
89
1:2.6
8
2d[b]
CH2Cl2
1
n/o
9
[c]
CH2Cl2
1
70%
2d
[d]
n/o 1.5:1
10
2d
THF
1
ChemComm Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: S. Medina, A. Henderson, J. Bower and M. C. Galan, Chem. Commun., 2015, DOI: 10.1039/C5CC02552D.
This is an Accepted Manuscript, which has been through the Royal Society of Chemistry peer review process and has been accepted for publication. Accepted Manuscripts are published online shortly after acceptance, before technical editing, formatting and proof reading. Using this free service, authors can make their results available to the community, in citable form, before we publish the edited article. We will replace this Accepted Manuscript with the edited and formatted Advance Article as soon as it is available. You can find more information about Accepted Manuscripts in the Information for Authors. Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal’s standard Terms & Conditions and the Ethical guidelines still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains.
www.rsc.org/chemcomm
Page 1 of 3
Journal Name
ChemComm
Dynamic Article Links ► View Article Online
DOI: 10.1039/C5CC02552D
Cite this: DOI: 10.1039/c0xx00000x
ARTICLE TYPE
www.rsc.org/xxxxxx
Stereoselective synthesis of glycosides using (salen)Co catalysts as promoters.
5
10
Received (in XXX, XXX) Xth XXXXXXXXX 20XX, Accepted Xth XXXXXXXXX 20XX DOI: 10.1039/b000000x The use of (salen)Co catalysts as a new class of bench-stable stereoselective glycosylation promoters of trichloroacetimidate glycosyl donors at room temperature is described. The conditions are practical and do not require the use of molecular sieves with products being isolated in good to high yields.
35
40
15
20
Access to structurally defined oligosaccharides in sufficient amounts to be used as probes for biological research, still represents a significant challenge due to the structural complexity of carbohydrates. The stereoselective coupling of glycosides is often considered the main bottleneck towards this goal and despite significant efforts devoted to the development of efficient glycosylation strategies, there is still a need for robust and practical methods to achieve this crucial step.1 Transition metal catalysis applied to oligosaccharide synthesis offers great promise at achieving high yields and anomeric selectivities by the careful choice of the metal and ligands attached to the metal centre.2
Table 1. Reaction optimization of trichloroacetimidate 3 with model acceptor 4a.
Entry
25
30
This journal is © The Royal Society of Chemistry [year]
Catalyst
Solvent
T (h)
Yield (%)
[a] α:β
1
1a
CH2Cl2
24
n/o
n/o
2
1b
CH2Cl2
22
89
1:1.5
3
1c
CH2Cl2
0.5
74
1.3:1
4
2a
CH2Cl2
24
64
1:2.6
5
2b
CH2Cl2
24
n/o
n/o
6
2c
CH2Cl2
22
70
1:2.6
7
2d
CH2Cl2
0.5
89
1:2.6
8
2d[b]
CH2Cl2
1
n/o
9
[c]
CH2Cl2
1
70%
2d
[d]
n/o 1.5:1
10
2d
THF
1
