The treatment of various 1,3-dihalides including the ones bearing an ester group with the titanocene(II) species produced cyclopropanes in good yields. The reaction of dihalides possessing two secondary halogens proceeded stereoselectively to afford trans-isomers as major products.
Stereospecific Synthesis of Enantioenriched Alkylidenecyclobutanones via Formal Vinylidene Insertion into Cyclopropanone Equivalents
作者:Christopher M. Poteat、Vincent N. G. Lindsay
DOI:10.1021/acs.orglett.1c02303
日期:2021.8.20
equivalents in a formal vinylidene insertion process, providing the first general synthetic route to enantioenriched alkylidenecyclobutanones. The addition of an alkenyl-Grignard reagent leads to an alkenylcyclopropanol capable of electrophilic activation by N-bromosuccinimide, triggering a regio- and stereospecific 1,2-migration and affording alkylidenecyclobutanones after elimination. Activation of the
Radical 3-exo-tet cyclization of 1,3-dihalopropanes with SmI2 to form cyclopropanes
作者:Tsuyoshi Ohkita、Yuhsuke Tsuchiya、Hideo Togo
DOI:10.1016/j.tet.2008.05.081
日期:2008.7
The preparation of 1,1-disubstituted and monosubstituted cycloproparres from corresponding 2,2-disubstituted and 2-monosubstituted 1,3-dihalopropanes, respectively, with SMI2 in THF was efficiently carried out. The reaction mechanism was proposed to proceed in a radical 3-exo-tet manner based on Baldwin's rule. (c) 2008 Elsevier Ltd. All rights reserved.
3-exo-tet Cyclization of 2,2-disubstituted 1,3-dihalopropanes with indium in aqueous and ionic liquid solvent system
作者:Yuhsuke Tsuchiya、Yuhta Izumisawa、Hideo Togo
DOI:10.1016/j.tet.2009.06.123
日期:2009.9
The 3-exo-tet cyclization of 2,2-disubstituted 1,3-dihalopropanes with In powder in THF solution of 20% H2O, dioxane solution of 20% H2O, and ionic liquids, such as [bmim]Br, [bmim]Cl, and [bmin]BF4, respectively, was efficiently carried out to form the corresponding 1,1-disubstituted cyclopropanes in good yields. The cyclopropanation of 2,2-disubstituted 1,3-dihalopropanes with In powder in ionic liquids, such as [bmim]Br, [bmim]Cl, and [bmin]BF4, was markedly accelerated compared with that in a THF solution of 20% H2O and a dioxane solution of 20% H2O. The mechanism was proposed to involve the radical 3-exo-tet cyclization of the formed 3-halopropyl radical. (C) 2009 Elsevier Ltd. All rights reserved.