Total synthesis of (S)‐(+)‐ent‐phomapyrones B and surugapyrone B

Phomapyrone B (1), the 2‐pyrones isolated from the phytopathogenic fungus Leptosphaeria maculans, has been synthesized as the enantiomeric form starting from (S)‐2‐methylbutanol (4). Surugapyrone B (3) isolated from Streptmyces sp. USF‐6280 as an antioxidant has also been synthesized as a natural form. The absolute configuration of phomapyrone B (1) was estimated to be the (R)‐form and that of surugapyrone B (3) being the (S)‐form. A series of 2‐pyrone derivatives 17 have been synthesized through the established procedure and their DPPH radical‐scavenging activities have also been evaluated.