dichotomous behaviour of the catalytic system generated from imidazoliniumsalts makes possible the preparation of cycloisomerisation products, or metathesis compounds when the reaction is carried out in the presence of acetylene. Finally, the possibility of performing ring-closing metathesis in imidazolium salts as an ionic solvent with an ionic catalyst of the type [(p-cymene)RuCl(PCy3)CCCPh2][X] is demonstrated
Facile Synthesis of Bicyclic and Tricyclic Skeletons by Cycloisomerizations of Hept-1-en-6-ynes and 4,9-Diheteradodeca-1,11-dien-6-ynes, Followed by [4 + 2] Cycloadditions
作者:Lonneke J. van Boxtel、Stefanie Körbe、Mathias Noltemeyer、Armin de Meijere
reaction with methyl acrylate, occurred with intramolecular transesterification to give the tricyclic lactones 11 (37%) and 16 (15%), respectively. Tricyclic systems containing up to three heteroatoms could be obtained from the corresponding dodeca-1,11-dien-6-ynes, by palladium-catalyzed cycloisomerization followed by intramolecular [4 + 2] cycloaddition. The scope and limitations of this single-operation
Unpredictable cycloisomerization of 1,11-dien-6-ynes by a common cobalt catalyst
作者:Abdusalom A Suleymanov、Dmitry V Vasilyev、Valentin V Novikov、Yulia V Nelyubina、Dmitry S Perekalin
DOI:10.3762/bjoc.13.62
日期:——
1,11-Dien-6-ynes undergo cycloisomerization in the presence of the cobalt catalytic system CoBr2/phosphine ligand/Zn/ZnI2 giving cyclohexene, diene or cyclopropane structures depending on the type of the phosphine ligand. This unpredictable behaviour suggests that, although the availability of the cobalt catalytic system is appealing, the development of well-defined catalysts is desirable for further
Ruthenium-Catalyzed [2 + 2 + 2] Cocyclization of Diene-yne
作者:Daisuke Tanaka、Yoshihiro Sato、Miwako Mori
DOI:10.1021/ja071954t
日期:2007.6.1
Ruthenium-catalyzed [2 + 2 + 2] cocyclization of diene-yne was developed. The reaction conditions were very mild; that is, a toluene solution of diene-yne was stirred in the presence of 5 mol % of Cp*Ru(cod)Cl. Tricyclic carbo- or heterocycles were obtained in high yields from corresponding straight carbon-chain compounds.
Nickel(0) Complexes of Acyclic Polyunsaturated Aza Ligands
The acydic 4,9-bis(4-tolylsulfonyl)-4,9-diazadodeca-1,11-dien-6-yne (1) and 4,9-bis(4-tolylsulfonyl)-4,9-diazatrideca-1,(E)-6-dien-11-yne (2), which differ in the sequence of the two ene and one yne functions in the chain, have been reacted with 1 and 2 equiv of Ni(cod)(2). The reaction with 1 equiv of Ni(cod)(2) affords the mononuclear trigonalplanar nickel(0) complexes 3 and 5. These react with a further 1 equiv of Ni(cod)(2) by addition of a Ni(cod) entity to give the dinuclear derivatives 4 and 6. While 3 forms a mixture of isomers C-2-3 and C-s-3 in solution, C-2-3 is exclusively present in the crystal, where it is packed in parallel columns. Complex 6 crystallizes as a spherulite. Complexes 3-6 have been characterized by NMR and single-crystal X-ray structure analysis, and a detailed conformational analysis is given.