NMR investigations of rotenoids

Extensive NMR studies of major rotenoids have (1) verified the cis B/C ring fusion of rotenone; (2) confirmed the structure of the reduction-dehydration product of rotenone; (3) provided considerable evidence regarding the preferred conformations of rotenoids; (4) revealed an array of long-range couplings; and (5) pointed up analytically useful solvent effects. Incidentally, these studies also allowed assignment of NMR signals for essentially all protons of the major rotenoids in deuterochloroform.