Low-valent Niobium Catalyzed Efficient Transformation Using Simple Alkenes

过渡金属催化的[2+2+2]不饱和化合物的环加成反应已被广泛研究，用于生成各种芳香和不饱和环化合物。在本研究中，我们报道了热稳定的低价Nb（III）化合物，NbCl_3（DME）或NbCl_5/(TMS)_3SiH作为催化剂，对末端炔、内炔和烯烃的多组分偶联[2+2+2]分子间环加成反应产生1,3 -环己二烯衍生物具有优异的产率和化学/区域选择性。

Transition-metal-catalyzed[2+2+2] cycloaddition of unsaturated compounds has been extensively studied for the formation of various aromatic and unsaturated cyclic compounds. In this study, we reported that thermally stable low-vallent Nb(III) compounds, NbCl_3(DME) or NbCl_5/(TMS)_3SiH provide as an efficient catalysts for the multi-component coupling[2+2+2] intermolecular cycloaddition reaction of terminal alkynes, internal alkynes and alkenes leading to 1, 3-cyclohexadiene derivatives as the desired products in excellent yield and chemo/regioselectivity.