title: Alkylative carbocyclization of omega-iodoalkynyl tosylates with alkynyllithium compounds through a carbenoid-chain process leading to (1-iodoprop-2-ynylidene)tetrahydrofurans and -cyclopropanes.
abstract: Alkylative carbocyclization reactions of omega-iodoalkynyl tosylates with alkynyllithium compounds to give products with incorporated iodine atoms are described. Slow addition of 2-(3-iodoprop-2-ynyloxy)ethyl tosylates to 1-alkynyllithium compounds in tetrahydrofuran at 40 degrees C followed by additional stirring at this temperature gives (Z)-3-(1-iodoprop-2-ynylidene)tetrahydrofurans stereoselectively in good to moderate yields. Under similar conditions at 0 degrees C, 4-iodobut-1-ynyl tosylates react with 1-alkynyllithium compounds to give (1-iodoprop-2-ynylidene)cyclopropanes. The carbocyclization reactions are proposed to proceed through a new carbenoid-chain process involving the exo cyclization of a lithium acetylide intermediate and the vinylic substitution of the resulting TsO,Li-cycloalkylidenecarbenoids (Ts=tosyl) by 1-alkynyllithium compounds.
authors.affiliation: Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan. harada@chem.kit.ac.jp
authors.forename: Toshiro
authors.initials: T
authors.lastname: Harada
authors.forename: Daisuke
authors.initials: D
authors.lastname: Imaoka
authors.forename: Chie
authors.initials: C
authors.lastname: Kitano
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kusukawa