title: Rutheniun-catalyzed cycloisomerization of o-(ethynyl)phenylalkenes to diene derivatives via skeletal rearrangement.
abstract: Treatment of a series of 2',2'-disubstituted (o-ethynyl)styrenes with TpRu(PPh(3))(CH(3)CN)(2)PF(6) (10 mol %) in benzene (80 degrees C, 12-18 h) efficiently gave 2-alkenyl-1H-indene derivatives. This catalytic reaction represents an atypical enyne cycloisomerization with skeletal rearrangement of starting enyne, where the C=C bond is completely cleaved and inserted by the terminal alkynyl carbon. The reaction mechanism was elucidated by a series of deuterium and (13)C labeling experiments, as well as by changing the substituents at the phenyl moieties. The mechanism is proposed to involve the following key steps: 5-endo-dig cyclization of ruthenium-vinylidene intermediate, a nonclassical ion formation, and the "methylenecyclopropane-trimethylenemethane" rearrangement.
authors.affiliation: Department of Chemistry, National Tsing-Hua University, Hsinchu 30043, Taiwan, Republic of China.
authors.forename: Reniguntala J
authors.initials: RJ
authors.lastname: Madhushaw
authors.forename: Ching-Yu
authors.initials: CY
authors.lastname: Lo
authors.forename: Chun-Wei
authors.initials: CW
authors.lastname: Hwang
authors.forename: Ming-Der
authors.initials: MD
authors.lastname: Su
authors.forename: Hung-Chin
authors.initials: HC
authors.lastname: Shen
authors.forename: Sitaram
authors.initials: S
authors.lastname: Pal
authors.forename: Isak R
authors.initials: IR
authors.lastname: Shaikh
authors.forename: Rai-Shung
authors.initials: RS
authors.lastname: Liu