title: Protective group-free syntheses of (±)-frontalin, (±)-endo-brevicomin, (±)-exo-brevicomin, and (±)-3,4-dehydro-exo-brevicomin: racemic pheromones with a 6,8-dioxabicyclo[3.2.1]octane ring.
abstract: Protective group-free syntheses of four racemic pheromones with a 6,8-dioxabicyclo[3.2.1]octane ring were achieved in five or six steps from commercially available (±)-3-butyn-2-ol (6) and 2-alkenyl halides or 2-alken-1-ol by employing Lewis acid-catalyzed acetalization of δ, ε-epoxy ketones as the key reaction. (±)-Frontalin (1) was prepared in a 25% overall yield in five steps from methallyl chloride (5a), (±)-endo-brevicomin (2) was prepared in a 23% overall yield in five steps from (E)-2-pentenyl bromide (5b), and (±)-exo-brevicomin (3) and (±)-3,4-dehydro-exo-brevicomin (4) were both prepared in a 4% overall yield in six steps based on (Z)-2-penten-1-ol (12).
authors: Photosensitive Materials Research Center, Toyo Gosei Co., Ltd, Chiba, Japan. kjk-mori@arion.ocn.ne.jp
authors: Kenji
authors: K
authors: Mori