Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58102, United States.
J Am Chem Soc. 2015 May 20;137(19):6136-9. doi: 10.1021/jacs.5b02272. Epub 2015 May 5.
A modular and atom-efficient synthesis of 2-aza-1,3-butadiene derivatives has been developed via nickel-catalyzed intermolecular coupling between internal alkynes and aromatic N-H ketimines. This novel alkyne hydroimination process is promoted by a catalyst system of a Ni(0) precursor ([Ni(cod)2]), N-heterocyclic carbene (NHC) ligand (IPr), and Cs2CO3 additive. The exclusive formation of (Z)-enamine stereoisomers is consistent with a proposed anti-iminometalation of alkyne by π-complexation with Ni(0) and subsequent attack by the N-H ketimine nucleophile. An NHC-ligated Ni(0) π-imine complex, [(IPr)Ni(η(1)-HN═CPh2)(η(2)-HN═CPh2)], was independently synthesized and displayed improved reactivity as the catalyst precursor.
一种通过镍催化的内部炔烃与芳族 N-H 亚胺酮之间的分子间偶联，实现了 2-氮杂-1,3-丁二烯衍生物的模块化和原子经济性合成。该新型炔烃氢亚胺化过程由 Ni(0)前体([Ni(cod)2])、N-杂环卡宾 (NHC)配体 (IPr)和 Cs2CO3添加剂的催化剂体系促进。(Z)-烯胺立体异构体的专一形成与炔烃通过与 Ni(0)的π-络合进行反亚胺金属化以及随后由 N-H 亚胺酮亲核试剂进攻的假设一致。独立合成了 NHC 配位的 Ni(0)π-亚胺配合物[(IPr)Ni(η(1)-HN═CPh2)(η(2)-HN═CPh2)]，并作为催化剂前体显示出提高的反应性。
