title: One-pot synthesis of metalated pyridines from two acetylenes, a nitrile, and a titanium(II) alkoxide.
abstract: Four-component coupling process involving two acetylenes, a nitrile, and a divalent titanium alkoxide reagent, Ti(O-i-Pr)(4)/2i-PrMgCl, directly yielded titanated pyridines in a highly selective manner. The reaction can be classified into four categories: (i) a combination of an internal acetylene, a terminal acetylene, sulfonylnitrile, and the titanium reagent to yield alpha-titanated pyridines, (ii) a combination of an internal acetylene, a (sulfonylamino)acetylene, a nitrile, and the titanium reagent to yield alternative alpha-titanated pyridines, (iii) a combination of an internal acetylene, a (sulfonylamino)acetylene, a nitrile, and the titanium reagent to yield titanated aminopyridines, and (iv) a combination of an acetylenic amide, a terminal acetylene, a nitrile, and the titanium reagent to yield pyridineamides with their side chain titanated. Some of these reactions enabled virtually completely regioselective coupling of two different, unsymmetrical acetylenes and a nitrile to form a single pyridine. Synthetic applications of these reactions have been illustrated in the preparation of optically active pyridines and medicinally useful compounds.
authors.affiliation: Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259-B-59 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8501, Japan.
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Tanaka
authors.forename: Akio
authors.initials: A
authors.lastname: Yuza
authors.forename: Yuko
authors.initials: Y
authors.lastname: Watai
authors.forename: Daisuke
authors.initials: D
authors.lastname: Suzuki
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