Secopaxilline A, an indole-diterpenoid derivative from an aciduric Penicillium fungus, its identification and semisynthesis

Secopaxilline A (1), a new meroditerpenoid derived from indole-diterpenoid by the oxidative cleavage of a carbon-nitrogen bond, was isolated from an aciduric fungus Penicillium camemberti OUCMDZ-1492. Its structure, including absolute configuration, was fully elucidated based on spectroscopic analysis and X-ray single crystal diffraction. Secopaxilline A is the first example of indole-diterpenoid derivatives possessing a carbon-nitrogen bond cleavage skeleton. It was synthesized from paxilline with a 45% overall yield. The one-pot synthesis of the biosynthetic precursor, deacetylsecopaxilline A (4), from paxilline was also developed.