4 research outputs found
Regenerative Glycosylation under Nucleophilic Catalysis
This article describes 3,3-difluoroxindole
(HOFox)-mediated glycosylation.
The uniqueness of this approach is that both the in situ synthesis
of 3,3-difluoro-3<i>H</i>-indol-2-yl (OFox) glycosyl donors
and activation thereof can be conducted in a regenerative fashion
as is a typical reaction performed under nucleophilic catalysis. Only
a catalytic amount of the OFox imidate donor and a Lewis acid activator
are present in the reaction medium. The OFox imidate donor is constantly
regenerated upon its consumption until glycosyl acceptor has reacted
HPLC-Assisted Automated Oligosaccharide Synthesis: Implementation of the Autosampler as a Mode of the Reagent Delivery
The development of a useful methodology
for simple, scalable, and
transformative automation of oligosaccharide synthesis that easily
interfaces with existing methods is reported. The automated synthesis
can now be performed using accessible equipment where the reactants
and reagents are delivered by the pump or the autosampler and the
reactions can be monitored by the UV detector. The HPLC-based platform
for automation is easy to setup and adapt to different systems and
targets
Regenerative Glycosylation
Previously, we communicated 3,3-difluoroxindole
(HOFox)-mediated
glycosylations wherein 3,3-difluoro-3<i>H</i>-indol-2-yl
(OFox) imidates were found to be key intermediates. Both the in situ
synthesis from the corresponding glycosyl bromides and activation
of the OFox imidates could be conducted in a regenerative fashion.
Herein, we extend this study to the synthesis of various glycosidic
linkages using different sugar series. The main outcome of this study
relates to enhanced yields and/or reduced reaction times of glycosylations.
The effect of HOFox-mediated reactions is particularly pronounced
in case of unreactive glycosyl donors and/or glycosyl acceptors. A
multistep regenerative synthesis of oligosaccharides is also reported
Surface-Tethered Iterative Carbohydrate Synthesis: A Spacer Study
Comparative
study of Surface-Tethered Iterative Carbohydrate Synthesis
(STICS) using HPLC-assisted experimental setup clearly demonstrates
benefits of using longer spacer-anchoring systems. The use of mixed
self-assembled monolayers helps provide the required space for glycosylation
reaction around the immobilized glycosyl acceptor. Both extension
of the spacer length and using mixed self-assembled monolayers help
promote the reaction, and the beneficial effects may include moving
the glycosyl acceptor further out into solution and providing additional
conformational flexibility. It is possible that surface-immobilized
glycosyl acceptors with a longer spacer (C8–O–C8)-lipoic
acid have a higher tendency to mimic a solution-phase reaction environment
than acceptors with shorter spacers