Two 7-membered ring derivatives of S-(-)-2, 2'-binaphthyl-diol, were synthesized. By comparing the X-ray diffraction structures and conformational analysis with optical rotatory values, the relationship between helical structures and optical rotations of compounds 2 and 3 were established. In addition, four rules for finding out helical segments were established and ω (the deviation value of s/l of a helix from 0.5774, which means the less the value of ω , the stronger its optical rotatory power) was defined, both are published for the first time.

Key words: NAPHTHALENOL P, HELICAL STRUCTURE, OPTICAL ROTATION, X- RAY DIFFRACTION ANALYSIS, CONFORMATION