Search

We have developed a Ni‐catalyzed cascade cyclization/Negishi‐coupling reaction for the formation of pyrrolidines and pyrrolidinones starting from N‐protected allylamines and acrylamides which contain a redox active ester group. The reaction provides two C−C bonds in a single operation and takes place with both alkylzinc and arylzinc bromides as nucleophiles. Activation of RAE by low valent Ni complexes involving a radical pathway followed by a fast cyclization of intermediate carbon radicals is proposed. [ABSTRACT FROM AUTHOR]

An iron‐catalyzed Kumada‐type cross‐coupling reaction of propargyl halides with alkylmagnesium reagents is described. The reaction is fast, takes place in smooth conditions, tolerates several functional groups that would be able to react with the Grignard reagent, and may afford either allene or propargyl coupling derivatives. Factors involved in the observed regioselectivity have been studied. [ABSTRACT FROM AUTHOR]

Conditions for the fast Ni-catalyzed Kumada-type cross-coupling of functionalized benzyl and allyl chlorides with alkylmagnesium reagents were discovered. The use of Ni(acac)2-TMEDA (acac = acetylacetonate, TMEDA = N, N, N′, N′-tetramethyl-1,2-ethylenediamine) allows the presence of reactive functional groups on the electrophile. On the other hand, the use of diallyl ether was shown to provide fast coupling at low temperature with a low catalyst loading. The reaction seems to follow a radical pathway. [ABSTRACT FROM AUTHOR]

Suggesting novel disconnections: A powerful Ni‐catalyzed cascade reaction involving cyclization followed by cross‐coupling allows the formation of up to three alkyl–alkyl bonds in a single operation by using alkene‐containing alkyl iodides and Grignard reagents (see scheme; acac=acetylacetonate; TMEDA=N,N′,N′‐tetramethyl ethylenediamine). Mechanistic experimental and computational studies suggest a NiI–NiII–NiIII catalytic cycle and the intermediacy of radicals. [ABSTRACT FROM AUTHOR]