Expedient total syntheses of preclathridine A and clathridine A

A short and operationally simple total synthesis of two Leucetta-derived marine alkaloids has been developed, which rely on position specific halogen–metal exchange to introduce the benzyl-substituted side chain. Introduction of the C2 amine group by lithiation and trapping with tosyl azide provides preclathridine A on catalytic hydrogenation, which can be converted to clathridine A by a procedure described in the literature.