1440058-41-2Relevant academic research and scientific papers
Role of Electron-Deficient Olefin Ligands in a Ni-Catalyzed Aziridine Cross-Coupling to Generate Quaternary Carbons
Estrada, Jesús G.,Williams, Wendy L.,Ting, Stephen I.,Doyle, Abigail G.
supporting information, p. 8928 - 8937 (2020/05/13)
We previously reported the development of an electron-deficient olefin (EDO) ligand, Fro-DO, that promotes the generation of quaternary carbon centers via Ni-catalyzed Csp3-Csp3 cross-coupling with aziridines. By contrast, electronically and structurally similar EDO ligands such as dimethyl fumarate and electron-deficient styrenes afford primarily β-hydride elimination side reactivity. Only a few catalyst systems have been identified that promote the formation of quaternary carbons via Ni-catalyzed Csp3-Csp3 cross-coupling. Although Fro-DO represents a promising ligand in this regard, the basis for its superior performance is not well understood. Here we describe a detailed mechanistic study of the aziridine cross-coupling reaction and the role of EDO ligands in facilitating Csp3-Csp3 bond formation. This analysis reveals that cross-coupling proceeds by a Ni0/II cycle with a NiII azametallacyclobutane catalyst resting state. Turnover-limiting C-C reductive elimination occurs from a spectroscopically observable NiII-dialkyl intermediate bound to the EDO. Computational analysis shows that Fro-DO accelerates turnover limiting reductive elimination via LUMO lowering. However, it is no more effective than dimethyl fumarate at reducing the barrier to Csp3-Csp3 reductive elimination. Instead, Fro-DO's unique reactivity arises from its ability to associate favorably to NiII intermediates. Natural bond order second-order perturbation theory analysis of the catalytically relevant NiII intermediate indicates that Fro-DO binds to NiII through an additional stabilizing donor-acceptor interaction between its sulfonyl group and NiII. Design of new ligands to evaluate this proposal supports this model and has led to the development of a new and tunable ligand framework.
Enantioselective Synthesis of β-Methyl Amines via Iridium-Catalyzed Asymmetric Hydrogenation of N-Sulfonyl Allyl Amines
Cabré, Albert,Verdaguer, Xavier,Riera, Antoni
, p. 4196 - 4200 (2019/08/16)
The iridium-catalyzed asymmetric hydrogenation of several N-sulfonyl allyl amines is reported. All substrates can be easily obtained by the Ir-catalyzed isomerization of N-tosylaziridines reported previously. The commercially available threonine-derived phosphinite (UbaPHOX) iridium complex has been found to be the best catalyst for this catalytic application, affording β-methyl amines with good to excellent ee values (up to 94%). The synthetic potential of this novel methodology was demonstrated by the formal synthesis of Lorcaserin and LY-404187. (Figure presented.).
Iridium-Catalyzed Isomerization of N-Sulfonyl Aziridines to Allyl Amines
Cabré, Albert,Sciortino, Giuseppe,Ujaque, Gregori,Verdaguer, Xavier,Lledós, Agustí,Riera, Antoni
supporting information, p. 5747 - 5751 (2018/09/21)
The Crabtree's reagent catalyzes the isomerization of N-sulfonyl 2,2-disubstituted aziridines to allyl amines. The selectivity of allyl amine vs imine is very high (up to 99/1). The unprecedented isomerization takes place in mild conditions without activation of the catalyst by hydrogen. The mechanism has been studied computationally by DFT calculations; instead of the usual hydrogenation of COD, the catalytic species is formed by a loss of the pyridine ligand. Approaching of aziridine to this unsaturated species leads to a carbocation intermediate through a low energy barrier. A metal-mediated tautomerization involving sequentially γ-H elimination and N-H reductive elimination affords selectively the allyl amine. The readiness of the CγH bond to participate in the H elimination step accounts for the selectivity toward the allyl amine product.
Iodine-Catalyzed Decarboxylative Amidation of β,γ-Unsaturated Carboxylic Acids with Chloramine Salts Leading to Allylic Amides
Kiyokawa, Kensuke,Kojima, Takumi,Hishikawa, Yusuke,Minakata, Satoshi
supporting information, p. 15548 - 15552 (2015/11/03)
The iodine-catalyzed decarboxylative amidation of β,γ-unsaturated carboxylic acids with chloramine salts is described. This method enables the regioselective synthesis of allylic amides from various types of β,γ-unsaturated carboxylic acids containing sub
Diverse reactivity in a rhodium(III)-catalyzed oxidative coupling of N-allyl arenesulfonamides with alkynes
Wang, Dongqi,Wang, Fen,Song, Guoyong,Li, Xingwei
, p. 12348 - 12352 (2013/02/23)
Olefinic CiH activation of N-allyl sulfonamides in the presence of [{RhCpCl2}2] (Cp=Me5C5) enabled their oxidative coupling with alkynes to generate 1,2-dihydropyridines, pyridines, and cyclopentenones (see scheme; Ts=p-toluenesulfonyl). The type of highly substituted product formed was controlled by the substitution of the allyl group and the reaction conditions. Copyright
