Iodocarbocyclization and Iodoaminocyclization Reactions Mediated by a Metallic Reagent

Osamu Kitagawa; Takeo Taguchi

doi:10.1055/s-1999-2790

Synlett 1999; 1999(8): 1191-1199
DOI: 10.1055/s-1999-2790

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Iodocarbocyclization and Iodoaminocyclization Reactions Mediated by a Metallic Reagent

Osamu Kitagawa^* , Takeo Taguchi

^*Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan; Fax and Tel. 814 26 76 32 57; E-mail: kitagawa@ps.toyaku.ac.jp and taguchi@ps.toyaku.ac.jp

Abstract

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We have developed new iodine-mediated carbocyclization and aminocyclization reactions through activation of intramolecular carbon or amide nucleophiles by metallic reagents. In the presence of I₂ and Ti(OR)₄ or TiCl₄-Et₃N, iodocarbocyclization of various active methine compounds having alkenyl or alkynyl groups proceeded in a highly stereospecific manner to give iodocyclo-alkanes or -alkenes in good yields. The present reaction can be also applied to asymmetric catalytic reation; that is, the reaction of 4-alkenylmalonate derivatives with Ti(TADDOLate)₂ catalyst gave iodoalkylcyclopentanes with excellent enantioselectivity (> 95%ee). Furthermore, iodoaminocyclization of unsaturated amide derivatives with an ambident nucleophilic center and iodoaziridination of N-allylic tosylamides, featuring regocontrol and an activation of an amide nucleophile by a basic metallic reagent, were also established.

iodocarbocyclization - iodoaminocyclization - iodine - metallic reagent - catalytic asymmetric reaction

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