alpha alpha-Disubstituted piperidines and conformationally constrained polyhydroxylated indolizidines bearing a hydroxymethyl substituent in position 8a were synthesized from a readily available L-sorbose-derived ketonitrone. Diastereoselective vinylation under two sets of complementary conditions allowed access to both configurations of the newly formed quaternary stereocenter. Subsequent N-allylation and ring-closing metathesis afforded 8a-branched indolizidines in high yield. The newly prepared iminosugars demonstrated highly potent inhibition of alpha-glucosidases. Most interestingly, compound 9b exhibits very high selectivity toward this class of enzymes, with an unusual mode of binding.
developed for the efficient synthesis of benzylidene acetal from aldehyde at room temperature. In this metal‐free method, Cl3CCN serves as a water scavenger as well as reaction medium and the acid catalyst is readily recovered and recycled. At room temperature, a wide variety of aryl and α,β‐unsaturated aldehydes react readily with functionalized diols and opticallyactive diols to furnish the corresponding
TEMPO-Mediated Anodic Oxidation of Methyl Glycosides and 1-Methyl and 1-Azido Disaccharides
作者:Matthias Schämann、Hans J. Schäfer
DOI:10.1002/ejoc.200390041
日期:2003.1
Methylglycosides of L-sorbopyranoside, D-fructopyranoside, D-glucosaminopyranoside, 2,3-dehydro-2,3-dideoxyglucopyranoside, cellobiose, lactose, and maltose and the 1-azido derivatives of glucose, cellobiose, lactose, and maltose have been converted into the corresponding uronic acids in moderate to excellent yields by TEMPO-mediatedanodicoxidation. The anode proves to be an advantageous alternative