title: Stereoselective synthesis of cycloheptanone derivatives via an intermolecular [5 + 2] cycloaddition reaction.
abstract: [reaction: see text] A [5 + 2] cycloaddition reaction of a new five-carbon unit was developed on the basis of a dicobalt hexacarbonyl propargyl cation species. Under the influence of EtAlCl(2), [5-benzoyloxy-2-(triisopropylsiloxy)-1-penten-3-yne)]dicobalt hexacarbonyl reacted with enol triisopropylsilyl ethers to yield seven-membered dicobalt acetylene complexes in good yield. The reactions with cyclic enol silyl ethers as well as acyclic enol silyl ethers exhibited remarkably high diastereoselectivity. The cycloadducts can be easily converted into various kinds of cycloheptanone derivatives.
authors.affiliation: Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan. ktanino@sci.hokudai.ac.jp
authors.forename: Keiji
authors.initials: K
authors.lastname: Tanino
authors.forename: Fumikatsu
authors.initials: F
authors.lastname: Kondo
authors.forename: Tadashi
authors.initials: T
authors.lastname: Shimizu
authors.forename: Masaaki
authors.initials: M
authors.lastname: Miyashita