29897-82-3Relevant articles and documents
Using a two-step hydride transfer to achieve 1,4-reduction in the catalytic hydrogenation of an Acyl pyridinium cation
Shaw, Anthony P.,Ryland, Bradford L.,Franklin, Mary J.,Norton, Jack R.,Chen, Judy Y.-C.,Hall, Michelle Lynn
, p. 9668 - 9674 (2008)
(Chemical Equation Presented) The stoichiometric reduction of N-carbophenoxypyridinium tetraphenylborate (6) by CpRu(P-P)H (Cp = η5-cyclopentadienyl; P-P = dppe, 1,2-bis(diphenylphosphino) ethane, or dppf, 1,1′-bis(diphenylphosphino)ferrocene), and Cp*Ru(P-P)H (Cp* = η5-pentamethylcyclopentadienyl; P-P = dppe) gives mixtures of 1,2- and 1,4-dihydropyridines. The stoichiometric reduction of 6 by Cp*Ru(dppf)H (5) gives only the 1,4-dihydropyridine, and 5 catalyzes the exclusive formation of the 1,4-dihydropyridine from 6, H 2, and 2,2,6,6-tetramethylpiperidine. In the stoichiometric reductions, the ratio of 1,4 to 1,2 product increases as the Ru hydrides become better one-electron reductants, suggesting that the 1,4 product arises from a two-step (e-/H?) hydride transfer. Calculations at the UB3LYP/6-311++G(3df,3pd)//UB3LYP/6-31G* level support this hypothesis, indicating that the spin density in the N-carbophenoxypyridinium radical (13) resides primarily at C4, while the positive charge in 6 resides primarily at C2 and C6. The isomeric dihydropyridines thus result from the operation of different mechanisms: the 1,2 product from a single-step H- transfer and the 1,4 product from a two-step (e-/H?) transfer.
Hydrosilylative reduction of primary amides to primary amines catalyzed by a terminal [Ni-OH] complex
Bera, Jitendra K.,Pandey, Pragati
, p. 9204 - 9207 (2021/09/20)
A terminal [Ni-OH] complex1, supported by triflamide-functionalized NHC ligands, catalyzes the hydrosilylative reduction of a range of primary amides into primary amines in good to excellent yields under base-free conditions with key functional group tolerance. Catalyst1is also effective for the reduction of a variety of tertiary and secondary amides. In contrast to literature reports, the reactivity of1towards amide reduction follows an inverse trend,i.e., 1° amide > 3° amide > 2° amide. The reaction does not follow a usual dehydration pathway.
N?N Bond Formation Using an Iodonitrene as an Umpolung of Ammonia: Straightforward and Chemoselective Synthesis of Hydrazinium Salts
Tota, Arianna,Colella, Marco,Carlucci, Claudia,Aramini, Andrea,Clarkson, Guy,Degennaro, Leonardo,Bull, James A.,Luisi, Renzo
supporting information, p. 194 - 199 (2020/10/28)
The formation of hydrazinium salts by N?N bond formation has typically involved the use of hazardous and difficult to handle reagents. Here, mild and operationally simple conditions for the synthesis of hydrazinium salts are reported. Electrophilic nitrogen transfer to the nitrogen atom of tertiary amines is achieved using iodosylbenzene as oxidant and ammonium carbamate as the N-source. The resulting process is highly chemoselective and tolerant to other functional groups. A wide scope is reported, including examples with bioactive molecules. Insights on the structure of hydrazinium salts were provided by X-ray analysis. (Figure presented.).
Continuous flow heterogeneous catalytic reductive aminations under aqueous micellar conditions enabled by an oscillatory plug flow reactor
?tv?s, Sándor B.,Buchholcz, Balázs,Darvas, Ferenc,Kappe, C. Oliver,Novák, Zoltán,Sipos, Gellért,Wernik, Michaela
supporting information, p. 5625 - 5632 (2021/08/16)
Despite the fact that continuous flow processing exhibits well-established technical advances, aqueous micellar chemistry, a field that has proven extremely useful in shifting organic synthesis to sustainable water-based media, has mostly been explored under conventional batch-based conditions. This is particularly because of the fact that the reliable handling of slurries and suspensions in flow has been considered as a significant technical challenge. Herein, we demonstrate that the strategic application of an oscillatory plug flow reactor enables heterogeneous catalytic reductive aminations in aqueous micellar media enhancing mass transport and facilitating process simplicity, stability and scalability. The micellar flow process enabled a broad range of substrates, including amino acid derivatives, to be successfully transformed under reasonably mild conditions utilizing only very low amounts of Pd/C as a readily available heterogeneous catalyst. The preparative capabilities of the process along with the recyclability of the heterogenous catalyst and the aqueous reaction media were also demonstrated. This journal is
