Treatment of eight C-seco limonoids including six of salannin-type, 1 - 6, and two of nimbin-type, 7 and 8, with a combination of BF3 · Et2 O and iodide ion yielded the isomeric C-seco derivatives, i.e., six isosalannins, 1a - 6a, and two isonimbins, 7a and 8a, respectively. Ohchinin (1) was further