Reaction Steps
PDC oxidation of 10-(2,3,4,6-tetra-O-benzyl-α-D-mannopyranosyloxy)-n-decanol. Under an atmosphere of nitrogen, pyridinium dichromate (400 mg, 1.036 mmol) was added to a dry methylene chloride solution (10 mL) of 10-(2,3,4,6-tetra-O-benzyl-α-D-mannopyranosyloxy)-n-decanol (450 mg, 0.646 mmol). The resulting brown slurry was stirred at room temperature under nitrogen. TLC analysis (visualization by UV and char with 10% sulfuric acid in ethanol) of the reaction mixture indicated complete consumption of the starting material and the formation of a new compound after 15 h. The reaction mixture was treated with ether (10 mL), filtered through silica gel and Celite with an ether wash (25 mL) and concentrated to an off-white oil. Chromatographic purification (silica gel, 20% ethyl acetate in hexanes) afforded 345 mg (0.497 mmol, 770%) of 10-(2,3,4,6-tetra-O-benzyl-α-D-mannopyranosyloxy)-n-decanal as a clear oil. Rf =0.50 (silica gel, 300 ethyl acetate in hexanes); 1H NMR (CDCl3, 300 MHz) δ: 9.76 (dt, J=5.1, 1.5 Hz, 1H), 7.31 (m, 20H), 4.93 (d, J=6.6 Hz, 1H), 4.91 (d, J=2.4 Hz, 1H), 4.78 (d, J=2.1 Hz, 1H), 4.72 (d, J=12.0 Hz, 1H), 4.67 (m, 2H), 4.57 (dd, J=12.0, 10.8 Hz, 2H), 4.09 (t, J=6.9 Hz, 1H), 4.03 (d, J=9.3 Hz, 1H), 3.96 (dd, J=12.0, 2.7 Hz, 1H), 3.82 (m, 3H), 3.68 (m, 1H), 3.40 (dt, J=9.6, 6.6, Hz, 2H), 2.41 (dt, J=7.2, 1.8 Hz, 2H), 1.64 (m, 4H), 1.32 (m, 12H); MS (FAB+): 717.1 ((M+Na)+, 33), 701.1 ((M+Li)+, 100), 671.1 (8), 615.1 (7), 455.1 (12), 439.1 (10), 423.1 (20), 243.1 (10), 181.1 (17), 160.0 (20).
