Studies On Synthesis Of L-menthyl-β-d-glycopyranoside And Protected Gal(α1â†'2)glc

Carbohydrates, proteins, nucleic acids and lipids play the most important role in life activities. With the deepening research on carbohydrates, their effects are increasingly reflected in many biological processes and they become the research frontier and focus of chemistry and life science. Because of diversity and structural complexity of carbohydrates, synthetic studies are mainly concentrated on the biologically active fragments of the glycosides at present. This paper studies a series of glycoside compounds with biological significance:two kinds of L-Menthyl-P-D-Glycopyranoside and eight kinds of protected Gal(α1→2)Glc.Menthol glycosides as a derivative of menthol which increase the water solubility and thermal stability can be widely used in flavor and drug. L-menthyl-β-D-glucopyranoside and L-menthyl-β-D-galactopyranoside were synthesized with glucose, galactose and menthol as the raw material after multi-step reaction such as protection, coupling and deprotection. Trichloroacetimidate, thioglycoside and other methods were used to synthesize L-menthyl-β-D-gluco pyranoside. On the comparison of these methods, L-menthyl-β-D-glucoside was synthesized by directly coupled 1,2,3,4,6-penta-O-acetyl-β-D-glucopyranose with L-menthol, and the coupling reaction conditions was optimized. By comparing three different methods, isopropyl-2,3,4,6-tetra-O-benzoyl-β-D-1-thiogalactopyranoside and menthol were chosen to efficient stereospecific synthesis of L-menthyl-β-D-galactopyranoside.Gal(α1→2)Glc as a part of Gal(α1→2)Glc(α1→3)acyl2Gro existing in sugar chain structures of lipoteichoic acid (LTA) and L.monocytogenes has important biological activity. The key to synthesis of Gal(α1→2)Glc is efficient buildα-1,2-cis glycoside. Based on this, we have used isopropyl-2-O-acetyl-3-O-allyl-4,6-O-benzylidene-β-D-1-thiogalactopyranoside and isopropyl-2-O-benzoyl-3-O- allyl-4,6-O-benzylidene-β-D-1-thiogalactopyranoside as the donors to react with acceptors methyl-3-O-benzoyl-4,6-O-benzylidene-a-D-glucopyranoside,methyl-3,4,6-O-benzo-yl-α-D-glucopyranoside, methyl-3-O-benzoyl-4,6-O-benzylidene-β-D-glucopyrano-side and methyl-3,4,6-O-benzoyl-β-D-glucopyranoside, and obtained eight kinds of protected Gal(α1→2)Glc. In these reactions, using isopropyl-2-O-benzoyl -3-O-allyl-4,6-O- benzylidene-β-D-1-thiogalactopyranoside as the donor to coupling react with acceptors methyl-3-O-benzoyl-4,6-O-benzylidene-α-D-glucopyranoside and methyl-3,4,6-O-benzoyl-β-D-glucopyranoside, the a-galactopyranoside was stereo-specific obtained.Synthesis of two kinds of L-Menthyl-β-D-Glycopyranoside and eight kinds of protected Gal(α1→2)Glc, provides materials to build glycoside efficiently and feasible approachs to synthesis of carbohydrate compounds especially. All studies of this paper are beneficial to developments and applications of related carbohydrate products.