title: Zirconocene-mediated intermolecular coupling of Si-tethered diynes with alkynes, ketones, aldehydes, and isocyanates by means of novel skeletal rearrangement of zirconacyclobutene-silacyclobutene and zirconacyclohexadiene-silacyclobutene fused-ring intermediates.
abstract: Bis(alkynyl)silanes react with low valent zirconocene species to afford zirconacyclobutene intermediates. These in situ generated reactive organometallic intermediates can react with alkynes, ketones, aldehydes, and isocyanates by means of a novel skeletal rearrangement. When a zirconacyclobutene intermediate was treated with an alkyne, an alpha-alkynylsilyl zirconacyclopentadiene was formed. Addition of dimethyl acetylenedicarboxylate (DMAD) and CuCl resulted in one-pot formation of an alkynylsilyl-benzene derivative from three different alkynes. At a higher temperature, the alpha-alkynylsilylzirconacyclopentadiene was transformed by means of an intramolecular skeletal rearrangement to a zirconacyclohexadiene-silacyclobutene fused-ring compound, which reacted with DMAD in the presence of CuCl affording the same alkynylsilyl-benzene derivative. When treated with a ketone, an aldehdye, or an isocyanate, the zirconocyclobutene intermediate also underwent the above-mentioned skeletal rearrangement, generating zirconocene-mediated cross-coupling products.
authors.affiliation: Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Yu
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Sun
authors.forename: Congyang
authors.initials: C
authors.lastname: Wang
authors.forename: Liang
authors.initials: L
authors.lastname: Deng
authors.forename: Zhenfeng
authors.initials: Z
authors.lastname: Xi