Expedient synthesis of the tetracyclic core of ent-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.