Expedient Synthesis of the Tetracyclic Core of <i>ent</i>-Nakadomarin A

An efficient eight-step assembly of the tetracyclic core (ABCD rings) of ent-(+)-nakadomarin A, a bioactive hexacyclic marine alkaloid, has been realized with Sonogashira coupling, platinum(II)-promoted cascade cyclizations, and saturation of a challenging carbon−carbon double bond through a hydroboration/oxidation/xanthate formation/Barton−McCombie deoxygenation sequence as key transformations.