抄録
Based on 1,2,3-triols 1a〜d, 1,2,3,4-tetraols 2a〜h, and 1,2,3,4,5-pentaols 3a〜p, NMR databases with four types of profile-descriptors (^<13>C-, ^1H-, and ^1H(OH)-chemical shifts and vicinal spin-coupling constants) for contiguous polyols are reported. To assess systematically the relative values of these databases, a case study has been conducted on heptaols 4a〜d, through which the γ-and δ-effects have been recognized to refine the ^<13>C and ^1H chemical shift profile predicted via an application of the concept of self-contained nature. The magnitudes of γ- and δ-effects depend on a specific stereochemical arrangement of the functional groups present in both the inside and outside of a self-contained box and are significant only for the stereoisomers belonging to a specific sub-group. With the exception of the stereochemical arrangement of functional groups belonging to a specific sub-group, the γ- and δ-effects can, at the first order of approximation, be ignored for the stereochemical analysis of unknown compounds. For the stereoisomers belonging to a specific sub-group, it is necessary to refine, with incorporation of the γ- and δ-effects, the profile predicted at the first order of approximation. With use of heptaols 4a〜d, the values of ^3J_<H,H> profiles have been assessed. Three methods using profiles of ^3J_<H,H> constant with three contiguous configurations, profiles consisting of three contiguous ^3J_<H,H> constants, and profiles consisting of two contiguous ^3J_<H,H> constants, have been developed. A stereochemical assignment of heptaols 4a〜d based on these three ^3J_<H,H> profiles are conducted very simply and clearly. The approach by using the logics with Universal NMR Databases (^<13>C-δ, ^1H-δ, ^3J_<H,H>) developed for a case of contiguous polyols should be applicable for other structural cluster in (acyclic) natural products as well.
