De novo asymmetric synthesis of all-D-, all-L-, and D-/L-oligosaccharides using atom-less protecting groups.
Oligosaccharide synthesis is hindered by the need for multiple steps as well as numerous selective protections and deprotections. Herein we report a highly efficient de novo route to various oligosaccharide motifs, of use for biological and medicinal structure activity studies. The key to the overall efficiency is the judicious use of asymmetric catalysis and synthetic design. These green principles include the bidirectional use of highly stereoselective catalysis (Pd(0)-catalyzed glycosylation/post-glycosylation). In addition, the chemoselective use of C-C and C-O π-bond functionality, as atom-less protecting groups as well as an anomeric directing group (via a Pd-π-allyl), highlights the atom-economical aspects of the route to a divergent set of natural and unnatural oligosaccharides (i.e., various d-/l-diastereomers of oligosaccharides as well as deoxysugars which lack C-2 anomeric directing groups). For example, in only 12 steps, the construction of a highly branched heptasaccharide with 35 stereocenters was accomplished from an achiral acylfuran.
Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115, USA.
Ravula Satheesh
RS
Babu
Qian
Q
Chen
Sang-Woo
SW
Kang
Maoquan
M
Zhou
George A
GA
O'Doherty
D002384:Catalysis; D006031:Glycosylation; D055772:Green Chemistry Technology; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000737:chemistry; D010165:Palladium / Q000737:chemistry; D013237:Stereoisomerism
D009844:Oligosaccharides; D010165:Palladium