X-RAY AND NMR-STUDIES ON THE ROTATIONAL-ISOMERISM ABOUT THE C(5)-C(6) BOND OF 6-SUBSTITUTED METHYL 2,3,4,-TRI-O-ACETYL-6-X-ALPHA-D-GLUCOPYRANOSIDE DERIVATIVES

The rotamers about the C(5)-C(6) bond of a series of 2,3,4-tri-O-acetyl-6-X-alpha-D-glucopyranozide derivatives resulting by substitution at C(6) or O(6) have been studied with H-1-NMR spectroscopy (400 MHz) and X-ray structure analysis. The methyl 2,3,4-tri-O-acetyl-6-O-triphenyl-methyl-alpha-D-glucopyranoside and the N-(1-O-methyl-2,3,4-tri-O-acetyl-alpha-D-glucopyranose-6-yl)- pyridinium nitrate crystallize in the P2(1) space group with a = 14.940(1), b = 11.232(1), c = 9.0773(7), and beta = 94.480(7) and a = 7.670(1), b = 15.384(3), c = 9.624(1) and beta = 104.90(1), respectively; the methyl 2,3,4-tri-O-acetyl-6-O-nitro-alpha-D-glucopyranoside and methyl 2,3,4-tri-O-acetyl-6-O-deoxy-6-iodo-alpha-D-glucopyrano-side crystallize in the P2(1)2(1)2(1) space group with a = 5.630(1), b = 14.360(1) and c = 22.388(3), and a = 5.556(1), b = 14.303(6) and c = 21.963(6), respectively.