This two-part article will focus on the most recent research efforts from t
he Wang's group in areas of glycochemistry and green chemistry. In the firs
t part, we wish to address the progress in synthesis, conformational analys
is, and transformations of some biologically active alpha-galactosyl oligos
accharides. Carbohydrate structures containing Gal alpha 1-3Gal beta termin
us (alpha-Gal epitopes) are xenoactive antigens and are considered to be th
e major cause for hyperacute rejection in xenotransplantation. The latest c
hemo-enzymatic synthesis of alpha-galactosyl epitopes using a recombinant a
lpha 1,3-galactosyltransferase is described. Along with an efficient chemic
al synthesis of an alpha-Gal trisaccharide, these synthetic approaches prov
ide an easy access to this important class of oligosaccharides. Conformatio
nal analysis of an alpha-Gal epitope using various NMR techniques and molec
ular modeling is discussed. These studies provide important information in
structure-function relationship and binding conformation of alpha-Gal epito
pes and their interaction with anti-Gal antibody. In another aspect, novel
glycoconjugates containing receptor-specific ligands and alpha-Gal epitopes
have been synthesized as potential immunotherapeutic agents.
The second part of this contribution summarizes our recent work in lanthani
de catalysis in aqueous media. The use of Ln(OTf)(3) in organic reactions,
including aza-Diels-Alder reaction, reactions of indole with aldehydes, and
catalysis on solid support is discussed. An emphasis is placed on the synt
hetic applications and their contribution to green technology by using envi
ronmentally friendly solvents.