ChemInform Abstract: Synthesis of the Lichen Macrolide (+)-Aspicilin Using Photolactonization as a Key Reaction.

ChemInform Abstract

The title compound (IX) is prepared starting from the Grignard reagent (I) (easily built up from phenol and 1,9-nonanediol) and the optically active oxirane (II); the latter determines the first stereogenic center. The key steps are the photolactonization of (V), the formation of the second stereogenic center by stereoselective reduction of the ketone (VII) using Yamamoto's reagent, and the pyridine-accelerated dihydroxylation of (VIII) to form the last two stereogenic centers. A second reaction pathway to the title compound is also investigated and the X-ray structures are given for a variety of intermediates, such as (VI) (space group Pcab, Z = 8), the acetate derived from (VIII) (P2₁/c, Z=4) and the triacetate of (IX) (P2₁2₁2₁, Z=4).