Understanding the Reactivity of Group 6 Metal (M = Cr, W) Alkynyl Fischer Carbene Complexes with Multi‐Reactive Masked Dienes,European Journal of Organic Chemistry

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Understanding the Reactivity of Group 6 Metal (M = Cr, W) Alkynyl Fischer Carbene Complexes with Multi‐Reactive Masked Dienes
European Journal of Organic Chemistry ( IF 2.5 ) Pub Date : 2018-07-03 , DOI: 10.1002/ejoc.201800453
Alba Collado ₁ , Mar Gómez-Gallego ₁ , Alicia Santiago ₁ , Miguel A. Sierra ₁

Affiliation

Group 6 alkynyl Fischer carbene complexes behave as electrophiles with highly reactive masked dienes such as anthrone and 3‐hydroxy‐2‐pyrone, which also can react as bidentate nucleophiles. Both Cr⁰ and W⁰ alkynyl carbene complexes require tertiary amines to promote the formation of 1,4‐C‐addition products, but a marked dependence of the reactivity on the metal was observed. Although W⁰ complexes form exclusively the 1,4‐C‐adducts in the presence of a catalytic amount of base, Cr⁰ complexes lead to new anthrone‐derived bis‐carbene complexes, obtained by a sequential 1,4‐C‐ and 1,4‐O‐addition process with high diastereoselectivity and only in the presence of an excess of base. DFT computational studies show that the gap between the LUMO of the complex and the HOMO of the anthrone determines the differences in reactivity and that the stability of the intermediate metal allenyls formed after the initial 1,4‐addition is decisive for the outcome of the reaction.

中文翻译：

了解具有多反应性掩蔽的二烯的6族金属（M = Cr，W）炔基菲舍尔碳络合物的反应性

第6组炔基菲舍尔卡宾配合物具有亲电性，具有高反应性的掩蔽二烯，如蒽酮和3-羟基-2-吡喃酮，它们也可以作为双齿亲核试剂反应。Cr ⁰和W ⁰炔基卡宾络合物均需要叔胺来促进1,4- C加成产物的形成，但观察到反应性对金属的显着依赖性。尽管W ⁰络合物仅在催化量的碱存在下形成1,4- C加合物，但Cr ⁰络合物却导致了新的蒽酮衍生的双卡宾络合物，它是由连续的1,4- C-和1获得的，4- Ô仅在存在过量碱的情况下，具有非对映选择性高的加成过程。DFT计算研究表明，配合物的LUMO和蒽酮的HOMO之间的间隙决定了反应性的差异，而且在最初的1,4加成后形成的中间金属烯基的稳定性对于反应的结果具有决定性的作用。。

更新日期：2018-09-17

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