title: An Efficient Route to 2,6-Disubstituted Styrenes via the Palladium-Catalyzed [4 + 2] Cyclodimerization of Conjugated Enynes.
abstract: An efficient and general method for the synthesis of 2,6-disubstituted styrenes 5 via the palladium-catalyzed [4+2] homobenzannulation of conjugated enynes 4 was developed. In all cases, the reactions proceeded in regiospecific manner, affording the disubstituted styrenes, bearing various functional groups at the 2 and 6 positions of the benzene ring, as a single reaction product in good to excellent yields. Initial attempts at cross-cycloaddition of two different enynes indicated low degrees of chemoselectivity of this process. Accordingly, the cross-dimerization products 6 in all cases were accompanied with notable amounts of the chemoisomeric homodimers 5.
authors.affiliation: Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Gevorgyan
authors.forename: Kazushi
authors.initials: K
authors.lastname: Tando
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Uchiyama
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Yamamoto