Synthesis of Alkaloid 223A and a Structural Revision

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