12151-13-2Relevant articles and documents
Tandem Nickel-Catalyzed Dimerization/(4+2) Cycloaddition of Terminal Alkynes with Four-Membered Ring Ketones
Barday, Manuel,Nicolas, Eva,Higginson, Bradley,Delmotte, Fran?ois,Appelmans, Martin,A?ssa, Christophe
, p. 1081 - 1090 (2021/12/02)
Controlling the behavior of terminal alkynes in metal-catalyzed intermolecular tandem reactions is a formidable challenge despite the potential advantage offered by these strategies in modern synthesis. Herein, we describe that a nickel catalyst enables a tandem process involving the rapid dimerization of terminal alkynes into 1,3-enynes and the cycloaddition of these intermediates with an azetidinone, an oxetanone or benzocyclobutenones. Significantly, the slow or sequential addition of reagents and catalysts is not required to orchestrate their reactivity. These results are in stark contrast with previous cycloadditions of terminal alkynes with strained four-membered ring substrates, which previously led to oligomerization or cyclotrimerization, except in the case of tert-butylacetylene.
Synergy between Experimental and Computational Chemistry Reveals the Mechanism of Decomposition of Nickel-Ketene Complexes
Staudaher, Nicholas D.,Arif, Atta M.,Louie, Janis
supporting information, p. 14083 - 14091 (2016/11/06)
A series of (dppf)Ni(ketene) complexes were synthesized and fully characterized. In the solid state, the complexes possess η2-(C,O) coordination of the ketene in an overall planar configuration. They display similar structure in solution, except in some cases, the η2-(C,C) coordination mode is also detected. A combination of kinetic analysis and DFT calculations reveals the complexes undergo thermal decomposition by isomerization from η2-(C,O) to η2-(C,C) followed by scission of the C=C bond, which is usually rate limiting and results in an intermediate carbonyl carbene complex. Subsequent rearrangement of the carbene ligand is rate limiting for electron poor and sterically large ketenes, and results in a carbonyl alkene complex. The alkene readily dissociates, affording alkenes and (dppf)Ni(CO)2. Computational modeling of the decarbonylation pathway with partial phosphine dissociation reveals the barrier is reduced significantly, explaining the instability of ketene complexes with monodentate phosphines.
Amino Acid Derived Nickelacycles: Intermediates in Nickel-Mediated Polypeptide Synthesis
Deming, Timothy J.
, p. 4240 - 4241 (2007/10/03)
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