title: Facile preparation of various heteroaromatic compounds via azatitanacyclopentadiene intermediates.
abstract: Coupling of acetylene, nitrile, and a titanium reagent, Ti(O-i-Pr)(4)/2 i-PrMgCl, generated new azatitanacyclopentadienes in a highly regioselective manner. Their subsequent reaction with sulfonylacetylene afforded pyridyltitanium compounds, which, upon reaction with electrophiles, gave substituted pyridines virtually as a single isomer. When optically active nitriles were used in this reaction, chiral pyridines were obtained without loss of the enantiopurity. Alternatively, the azatitanacyclopentadiene prepared from an unsymmetrical acetylene reacted with an aldehyde or another nitrile to give furans or pyrroles having four different substituents again in a regioselective manner.
authors.affiliation: Department of Biomolecular Engineering, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Midori-ku, Yokohama, Kanagawa, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Suzuki
authors.forename: Youhei
authors.initials: Y
authors.lastname: Nobe
authors.forename: Yuko
authors.initials: Y
authors.lastname: Watai
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Tanaka
authors.forename: Yuuki
authors.initials: Y
authors.lastname: Takayama
authors.forename: Fumie
authors.initials: F
authors.lastname: Sato
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Urabe