Vicinal diamines are ubiquitous materials in organic and medicinal chemistry. The direct coupling of olefins and amines would be an ideal approach to construct these motifs. However, alkene diamination remains a long‐standing challenge in organic synthesis, especially when using two different amine components. We report a general strategy for the direct and selective assembly of vicinal 1,2‐diamines using readily available olefin and amine building blocks. This mild and straightforward approach involves in situ formation and photoinduced activation of N‐chloroamines to give aminium radicals that enable efficient alkene aminochlorination. Owing to the ambiphilic nature of the β‐chloroamines produced, conversion into tetra‐alkyl aziridinium ions was possible, thus enabling diamination by regioselective ring‐opening with primary or secondary amines. This strategy streamlines the preparation of vicinal diamines from multistep sequences to a single chemical transformation.
Herein, we report a strategy for the generation of nitrogen‐radicals by ground‐state single electron transfer with organyl–Ni
I
species. Depending on the philicity of the N‐radical, two types of processes have been developed. In the case of nucleophilic aminyl radicals direct N‐arylation with aryl organozinc, organoboron, and organosilicon reagents was achieved. In the case of electrophilic amidyl radicals, cascade processes involving intramolecular cyclization, followed by reaction with both aryl and alkyl organometallics have been developed. The N‐cyclization–alkylation cascade introduces a novel retrosynthetic disconnection for the assembly of substituted lactams and pyrrolidines with its potential demonstrated in the short total synthesis of four venom alkaloids.
Vicinal diamines are ubiquitous materials in organic and medicinal chemistry. The direct coupling of olefins and amines would be an ideal approach to construct these motifs. However, alkene diamination remains a long‐standing challenge in organic synthesis, especially when using two different amine components. We report a general strategy for the direct and selective assembly of vicinal 1,2‐diamines using readily available olefin and amine building blocks. This mild and straightforward approach involves in situ formation and photoinduced activation of N‐chloroamines to give aminium radicals that enable efficient alkene aminochlorination. Owing to the ambiphilic nature of the β‐chloroamines produced, conversion into tetra‐alkyl aziridinium ions was possible, thus enabling diamination by regioselective ring‐opening with primary or secondary amines. This strategy streamlines the preparation of vicinal diamines from multistep sequences to a single chemical transformation.
The development of a nickel-catalysed strategy for the remote alkylation, arylation, vinylation and alkynylation of nitriles is presented. The methodology uses electron-poor O-Ar cyclic oximes and organozincs as coupling partners. This redox process proceeds through the generation of an iminyl radical and its following ring-opening reaction.
A common problem encountered in enantioselective organocatalysis is the aggregation of the catalyst, which can result in a relevant decrease of the efficiency and selectivity of the process. In the asymmetric synthesis of chiral benzofuranones, recently reported by us, we noted a remarkable increase of the reaction yield upon the addition of one of the reagents in a portionwise manner rather than in a single addition. We investigated this phenomenon by several experimental techniques such as 1D and 2D NMR experiments, UV-Vis spectroscopy, circular dichroism and dynamic light scattering. In addition, we studied the kinetic profile of this reaction using a simple numerical model and carried out in silico investigations. All these different approaches point to the conclusion that in the reaction medium a supramolecular polymerization/aggregation phenomenon, based on weak interactions, occurs and such a process is promoted by a quinone, which is one of the reagents of the benzofuranone synthesis. The portionwise mode of addition is a known strategy which can improve the performance of many synthetic procedures and this strategy is commonly adopted on account of empirical experience. However, our results provide an explanation, based on a chemical kinetic model, of the reason why the portionwise addition affects in such a dramatic way the yield of the benzofuranone synthesis catalyzed by Cinchona alkaloids.
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