ニッケル錯体を用いた新しいπ電子系の構築
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概要
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New Synthetic methods for preparing highly unsaturated compounds are developed by using the nickel-catalyzed cyclooligomerization of cumulenes, carbenoids, and benzocyclobutadiene, and the nickel-catalyzed Ullmann coupling of organic halides. [3] Cumulenes (butatrienes), which are generated in situ from various precursors, react with nickel (0) complexes to produce [4] radialenes in benzene and THF or [6] radialenes in DMF. The formation of dimers and trimers depends on the solvent used. Reaction of [5] cumulenes (hexapentaenes) with Ni (CO)<SUB>2</SUB> (PPh<SUB>3</SUB>)<SUB>2</SUB> yields very unique compounds containing radialene frameworks. Furthermore, reaction of nickel carbenoids proceeds formally as a cyclooligomerization of the carbene center to give [3] -, [4] -, and [5] radialenes. This one-step method has been applied to the synthesis of radialenes containing functional groups. The nickel-catalyzed Ullmann coupling of vinyl halides can be also achieved to give novel π-electron systems. Nickel-mediated synthesis of trimers of benzocyclobutadiene is demonstrated with mechanistic explanation.
- 社団法人 有機合成化学協会の論文