[Development of novel carbon-carbon bond forming reactions using zirconocene complex].
Novel zirconium-mediated carbon-carbon bond-forming reactions were developed. The allylic, gamma-alkoxyallylic, allenyl, and gamma, gamma-dialkoxyallylic zirconium species can be prepared from corresponding ethers under mild conditions through the addition of a zirconocene-butene complex to the carbon-carbon multiple bond of the ethers and subsequent beta-elimination of the alkoxyl group. The gamma,gamma-dialkoxyallylic zirconium species reacts with carbonyl compounds at the beta-position of the zirconium atom like a ketene dialkyl acetal in the presence of stoichiometric amounts of Lewis acid and gave cyclopropane and/or cyclobutane derivatives. Intramolecular reaction of allylic zirconium species with acetal also develops as a ring contraction reaction of carbohydrates and morpholine derivatives. This method is useful for the construction of chiral highly functionalized carbocycles and pyrrolidines. The intramolecular ester transfer reaction through the zirconium-mediated coupling reaction of alkenyl carbamates gave gamma-aminobutyric acid derivatives and pyrrolidine-3-carboxylic acids.
Ito
Hisanaka
H
School of Life Science, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji 192-0392, Japan. itohisa@ls.toyaku.ac.jp
D002244:Carbon / Q000737:chemistry*; D002625:Chemistry, Organic; D055601:Organic Chemistry Phenomena; D009942:Organometallic Compounds; D011759:Pyrrolidines / Q000138:chemical synthesis; D013237:Stereoisomerism; D015040:Zirconium; D005680:gamma-Aminobutyric Acid / Q000138:chemical synthesis
D009942:Organometallic Compounds; D011759:Pyrrolidines; C023398:Zirconocene dichloride; D005680:gamma-Aminobutyric Acid; D002244:Carbon; D015040:Zirconium; C032519:pyrrolidine