Meanwhile, an alternative, higher-energy conformer group (B-type conformers) (ΔG = +1.1 kcal/mol; 1B: the lowest-energy conformer in this group) is present in which all six hydroxy groups in the HHDP moiety adopt the same orientation, leading to intramolecular hydrogen bonding between 6-and 6′-hydroxy groups (Figure ). Such an intramolecular hydrogen bond reduces the dihedral angle between the two benzene rings in HHDP moiety relative to the A-type conformers (1A: 60.7°; 1B: 50.7°). Notably, comparison of the calculated C NMR chemical shifts for the Btype conformers with experimental data showed significantly improved agreement (ΔδC: +1.9 and +2.1 ppm for C-1 and C-1′ in the HHDP moiety, respectively, for the α-anomer of 1) (Table ),