title: Synthesis of phthalides and 3,4-dihydroisocoumarins using the palladium-catalyzed intramolecular benzannulation strategy.
abstract: A novel method for the synthesis of phthalides and 3,4-dihydroisocoumarins via the palladium-catalyzed intramolecular benzannulation of bis-enyne and enyne-diyne systems is described. Various kinds of substituted phthalides 9 and 17 and 3,4-dihydroisocoumarins 19 were synthesized from 8, 16, and 18, respectively, in moderate to excellent yields. The benzannulation reaction proceeded chemoselectively to give the corresponding fused ring compounds A without the formation of the regioisomeric products B (eq 6). Furthermore, this methodology was applied to the synthesis of biologically active 3-n-butylphthalide 23.
authors.affiliation: Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
authors.forename: Taishi
authors.initials: T
authors.lastname: Kawasaki
authors.forename: Shinichi
authors.initials: S
authors.lastname: Saito
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Yamamoto