Synthesis of alkaloid 223A and a structural revision

[GRAPHICS] Synthesis of alkaloid 223A has been achieved by sequential use of our original conjugate addition reaction to enaminoesters as the key step. The proposed structure for natural 223A (A, absolute configuration unknown) was revised to B, and the relative stereostructure was determined to be 5R*,6R*,8R*,9S* by the present synthesis.