Synthesis of Spongidine A and D and Petrosaspongiolide L Methyl Ester Using Pyridine C-H Functionalization.

An efficient strategy for the synthesis of the potent phospholipase A2 inhibitors spongidine A and D is presented. The tetracyclic core of the natural products was assembled via an intramolecular hydrogen atom transfer initiated Minisci reaction. A divergent late-stage functionalization of the tetracyclic ring system was also used to achieve a concise synthesis of petrosaspongiolide L methyl ester.