Detailed investigations on the use of nickel(0)-based catalysts for intramolecular [4+4]-cycloadditions are presented. Nickel(0) complexes derived from electron-rich triarylphosphines proved to be efficient catalysts for intramolecular [4+4]-cycloadditions of an array of structurally diverse bis-dienes (10 examples, up to 78% isolated yield). The reported synthetic methodology leads to cis-eight-membered fused [6.3.0] bicyclic compounds as well as trans- or cis-eight-membered fused [6.4.0] bicyclic systems. Computational studies on the stereo-determining step of the reaction in combination with experimental results demonstrated that the stereochemical outcome is dictated by the length of the chain linking the two diene units and the geometry of the CC double bonds of the substrates.

中文翻译：

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二烯的镍催化的分子内[4 + 4]-环加成反应向八元稠合双环系统的转化：实验和计算研究的组合†

提出了使用镍（0）基催化剂进行分子内[4 + 4]-环加成的详细研究。富含电子的三芳基膦衍生的镍（0）配合物被证明是分子内[4 + 4]-环加成的一系列结构多样的双二烯的有效催化剂（10个实例，分离产率高达78％）。报道的合成方法导致顺式-八元稠合的[6.3.0]双环化合物以及反式或顺式-八元稠合的[6.4.0]双环系统。关于反应的立体确定步骤的计算研究与实验结果相结合，表明立体化学结果由连接两个二烯单元的链的长度和C的几何形状决定底物的C双键。