Chemical reactivity of phthalides. Relay synthesis of diligustilide, rel-(3'R)-3',8'-dihydrodiligustilide and wallichilide

Article abstract of DOI:10.1016/S0040-4020(98)00080-5

Diels Alder reaction using Z-ligustilide (3) both as diene and dienophile afforded the natural product diligustilide (1). The relay synthesis of 5 from 1 (via situ-selective lactone ring opening, reduction with NaBH₄/MeOH and lactonization with SOCl₂/THF) was achieved and confirmed the revised structure of 5, a secondary constituent of Ligusticum wallichii. The natural substance wallichilide (8) was also obtained directly from 1.