N‐Bearing Furanone Derivatives from an Endophytic Fungus in Huperzia serrata

Two new polyketide derivatives, huaspenones C and D (1 and 2, resp.), were isolated from the cultures of an endophytic fungus Peyronellaea sp. HS-12, derived from the stems of Huperzia serrata. They share N-bearing furan-3(2H)-one backbone, and 2 has an unprecedented furo[3,2-c]pyridine skeleton. Their structures including the absolute configuration were elucidated by extensive spectroscopic analysis combined with quantum-chemical calculations. (2E,4E)-6-hydroxy-2-methylocta-2,4-dienoic acid (3), a key intermediate of the biosynthesis of 1 and 2, was also obtained from the endophyte.