title: C,C-diacetylenic phosphaalkenes in palladium-catalyzed cross-coupling reactions.
abstract: The reactivity of bis-TMS-substituted C,C-diacetylenic phosphaalkene (A(2)PA) 1 in Sonogashira-Hagihara cross-coupling reactions has been examined. The selective and successive deprotection of the two silyl groups in 1 is enabled by the steric bulk of the Mes* group which renders the acetylene trans to Mes* more reactive and thereby facilitates selective and consecutive couplings with iodoarenes. In situ transformation of the TMS-protected acetylenes into Cu(i)acetylides is the key step in the synthetic sequence and enables the preparation of the first dimeric A(2)PA linked by a phenylene spacer. cis-trans Isomerization across the P[double bond, length as m-dash]C bond is triggered by a tertiary amine and exclusively observed in the case of nitrophenyl-substituted A(2)PAs. The introduced aryl groups are integral parts of the entire π-system as evidenced by spectroscopic and electrochemical studies.
authors.affiliation: Department of Photochemistry and Molecular Science, Ångström Laboratories, Uppsala University, Uppsala, Sweden.
authors.forename: Elisabet
authors.initials: E
authors.lastname: Oberg
authors.forename: Xue-Li
authors.initials: XL
authors.lastname: Geng
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Santoni
authors.forename: Sascha
authors.initials: S
authors.lastname: Ott