This competing continuation application describes the invention and application of novel chemical transformations for the preparation of structurally unusual carbohydrates and oligosaccharides, which are important structural components of many compounds that exhibit anticancer, antimicrobial, and immunostimulating activities. Specific chemical transformations developed by the P.l.'s laboratory which will be applied in this research include the catalytic endoselective alkynol cycloisomerization reaction, as well as electrophile-promoted glycosylations including the conceptually simple but underexploited acid-catalyzed glycosylation for the synthesis of 2-deoxyglycosides. Other metal-catalyzed processes such as internally directed Heck reactions will also be utilized in the construction of branched glycosides. These transformations are the basis for unique strategies to the syntheses of O- and C-linked oligosaccharides which have many advantages over classical methods. For instance, the efficient stereoselective synthesis of alkynyl alcohol substrates is easily applied to the construction of oligosaccharides bearing unusual stereochemical and substitution patterns, as well as the highly deoxygenated oligosaccharides present in many compounds exhibiting anticancer and other therapeutic properties. ? ? Specific aims for the next funding period include continued methodology development for siteselective and stereoselective transformations of the glycal products obtained from alkynol cycloisomerization, in the context of projects directed at: ? (1) synthesis of trisaccharide natural products bearing beta-glycosides of 2,6-dideoxyglycosides of the arabino configuration (i.e. maryal); ? (2) synthesis of the altromycin C-glycoside family of antitumor antibiotics, including determination of unassigned elements of absolute and relative stereochemistry; and ? (3) partial synthesis of degradation products of the antibiotic saccharomicin natural products, including determination of absolute stereochemistry of the individual sugar components. ? ?
| Balthaser, Bradley R; McDonald, Frank E (2009) Brønsted acid-promoted glycosylations of disaccharide glycal substructures of the saccharomicins. Org Lett 11:4850-3 |
| Koo, Bonsuk; McDonald, Frank E (2007) Fischer carbene catalysis of alkynol cycloisomerization: application to the synthesis of the altromycin B disaccharide. Org Lett 9:1737-40 |
| Fei, ZhongBo; McDonald, Frank E (2007) Stereo- and regioselective glycosylations to the bis-C-arylglycoside of kidamycin. Org Lett 9:3547-50 |
| Koo, Bonsuk; McDonald, Frank E (2005) Synthesis of the branched C-glycoside substructure of altromycin B. Org Lett 7:3621-4 |
| Fei, ZhongBo; McDonald, Frank E (2005) Synthesis of the aglycones of altromycins and kidamycin from a common intermediate. Org Lett 7:3617-20 |
| Nowroozi-Isfahani, Taraneh; Musaev, Djamaladdin G; McDonald, Frank E et al. (2005) Density Functional Study of Mo-Carbonyl-Catalyzed Alkynol Cycloisomerization: Comparison with W-Catalyzed Reaction. Organometallics 24:2921-2929 |
