The first electrochemical approach for nickel‐catalyzed cross‐electrophile coupling was developed. This method provides a novel route to 1,1‐diarylalkane derivatives from simple and readily available alkyl and aryl halides in good yields and excellent regioselectivity under mild conditions. The procedure shows good tolerance for a broad variety of functional groups and both primary and secondary alkyl halides can be used. Furthermore, the reaction was successfully scaled up to the multigram scale, thus indicating potential for industrial application. Mechanistic investigation suggested the formation of a nickel hydride in the electroreductive chain‐walking arylation, which led to the development of a new nickel‐catalyzed hydroarylation of styrenes to provide a series of 1,1‐diaryl alkanes in good yields under mild reaction conditions.
This focused review aims to summarize recent developments in the processes involving additions of secondary propargylamines to various heteroallenes and subsequent transition metal-catalyzed or electrophile-mediated cyclizations. The utility of this convenient and tunable strategy spans from the carbon dioxide fixation and target-oriented synthesis of complex natural and biologically active products to the generation of extended synthetic libraries of diverse oxygen-, nitrogen- and sulfur-containing heterocycles. For comparative purposes, the analogous transformations of propargylic alcohols are also highlighted in this account.
A novel procedure for the Heck-Suzuki tandem reaction suitable for the construction of nitrogen-containing medium rings was developed to provide access toward the 3-benzazepine framework.
A silver(I) triflate‐catalyzed protocol for the post‐Ugi synthesis of tetracyclic spiroindolines has been developed. The protocol worked best for indole‐3‐carbaldehyde‐derived Ugi adducts obtained using anilines and 3‐aryl propiolic acids. Thus, it is complementary to the previous cationic gold‐catalyzed procedure that was developed for analogues Ugi substrates derived from aliphatic amines and 3‐alkyl propiolic acids. Furthermore, we have demonstrated that under our new settings this domino Friedel‐Crafts ipso cyclization / imine trapping process could be efficiently combined with the preceding four‐component Ugi reaction into a two‐step one‐pot transformation.
Cationic gold-catalyzed cycloisomerizations of propargylureas, derived in situ from secondary propargylamines and aryl or alkyl isocyanates, have been studied. The reaction outcome was found to be different from what was previously observed for the tosyl isocyanate-derived ureas in terms of both regio- and chemoselectivity. As a result, the current protocol offers efficient access to the 3,4-dihydropyrimidin-2(1H)-one core through the 6-endo-dig N-cyclization.
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