N-heterocyclic Carbene Catalyzed Stereoselective Glycosylation Of 2-nitrogalactals

2-Deoxy-2-amino-substituted glycosides are ubiquitous compounds in biochemistry and biology,which participate in organic life process of cancer metastasis,inflammation,immune defense,fertilization,metabolism,neuronal signaling,cell growth,cell adhesion,cell recognition.Among them,2-acetamido-2-deoxy-D-O-galactopyranosides are the most common units in a number of proteins such as mucins,cell membrane lycoproteins,immunoglobulins,and antifreeze glycoproteins.Though some stereoselective glycosylation of 2-nitro galactals have been developed,the substrate scope and the steroselectivity control still remain under developed.Thus,exploring economic,highly stereoselective method to construct glycosidic is desirable.This thesis is divided into two parts.The first chapter reviewed organocatalyzed reaction of 2-nitroglycals to construct O,S and N-glycoside stereoselectively during the past twenty years.Including Michael addition reaction of alcohol/phenol or thiol/thiophenol to 2-nitroglycals.The second chapter introduced N-heterocyclic carbene catalyzed stereoselective glycosylation of 2-nitrogalactals.An efficient N-heterocyclic carbene catalyzed glycosylation of 2-nitrogalactals with alcohols and phenol has been developed for the first time.A wide variety of 1,2-cis-2-nitroglycosides can be obtained with good to excellent yields and high to excellent ?-selectivities.