ROTATIONAL ISOMERISM ABOUT THE C-5-C-6 BOND OF 6-O-TRITYL DERIVATIVES OF ALDOHEXOPYRANOSES, AND OF ANALOGS OF D-GALACTOPYRANOSE MODIFIED AT C-4

Article abstract of DOI:10.1016/0008-6215(86)80003-9

Differences in rotational isomerism about the C-5-C-6 bond of 4-O-acetyl-6-O-tritylaldohexopyranose derivatives in the gluco and manno, as compared with the galacto, series are reflected in different contributions towards diamagnetic shielding of the acetoxyl protons, and rotatory characteristics of the compounds.Among 4-deoxy-4-halogeno analogs of methyl β-D-galactopyranoside, rotational isomerism varies little, based on H-5,6,6' coupling, whereas the 6,6'-protons exhibit enhanced anisochronism as the mass of the halogen atom increases.The identification of resonance signals due to H-6_R and H-6_S, respectively, provides a basis for the consideration of these findings.