Palladium Catalyzed Allylation Of Glycal With Nitroalkane

C-glycoside is an important biological macromolecule in the process of life activities.It exists widely in nature.Because of its good enzyme stability,potential biological activity and important role in drug design,the synthesis of such compounds has received more and more attention in recent years.Transition metal catalyzed coupling reaction and chiral square amine reagent-assisted nitromethylene sp³ C-H bond activation strategy were combined to realize C-glycosides with highα/β-selectivity and R/S diastereoselective synthesis using 3,4-O-carbonate glycal donors and nitroalkane as acceptors.Twenty-eightβ-（R/S）-C-glycoside derivatives with different substituent types and eightβ-C-glycoside containing 2,3-unsaturated glycoside backbone were synthesized.This method achieved efficient and diastereoselective synthesis ofβ-C-glycoside derivatives.The yield of nitromethane glycosides was as high as 93%.The absolute structure ofβ-（R/S）-C-glycoside derivatives were finally determined by ¹H NMR,¹³C NMR,¹H ¹H COSY,HSQC,HMBC,NOESY,circular dichroic spectroscopy,X-ray crystal diffraction.The ratio of epimerization（R/S）was determined by HPLC detection,and the experimental results achieved the expected experimental purpose.This method has an onlyβ-C-glycoside selectivity,and initially realizes the selective control of diastereomers（R/S）.Some intermediates and C-glycosides have been tested for their inhibitory effects onα-glucosidase,and related activity tests were underway.This work was an important supplement for the asymmetric synthesis of carbon glycoside compounds with multiple functional group structures.