title: Novel phosphine-catalyzed zipper cyclization of aliphatic diyne-dione and yne-dione systems.
abstract: [reaction: see text] An unexpected tri-n-butylphosphine-catalyzed zipper cyclization of diyne[bond]diones (1a-d) or yne-diones (1e and 1f) is described. Bicyclic ketones (2a, 2b, 2c, 2e, and 2f) with five- or six-membered rings fused to the five-membered ring were obtained from both aliphatic diyne-diones (1a-c) and yne-diones (1e and 1f) having tetra- or pentamethylene spacers. The bicyclic products (2) were produced with high diastereoselectivity.
authors.affiliation: Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuta-cho 4259, Midori-ku, Yokohama 226-8502, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Kuroda
authors.forename: Ikuyoshi
authors.initials: I
authors.lastname: Tomita
authors.forename: Takeshi
authors.initials: T
authors.lastname: Endo