58202-83-8Relevant academic research and scientific papers
Nitrogen Atom Transfer Catalysis by Metallonitrene C?H Insertion: Photocatalytic Amidation of Aldehydes
Schmidt-R?ntsch, Till,Verplancke, Hendrik,Lienert, Jonas N.,Demeshko, Serhiy,Otte, Matthias,Van Trieste, Gerard P.,Reid, Kaleb A.,Reibenspies, Joseph H.,Powers, David C.,Holthausen, Max C.,Schneider, Sven
, (2022/01/20)
C?H amination and amidation by catalytic nitrene transfer are well-established and typically proceed via electrophilic attack of nitrenoid intermediates. In contrast, the insertion of (formal) terminal nitride ligands into C?H bonds is much less developed and catalytic nitrogen atom transfer remains unknown. We here report the synthesis of a formal terminal nitride complex of palladium. Photocrystallographic, magnetic, and computational characterization support the assignment as an authentic metallonitrene (Pd?N) with a diradical nitrogen ligand that is singly bonded to PdII. Despite the subvalent nitrene character, selective C?H insertion with aldehydes follows nucleophilic selectivity. Transamidation of the benzamide product is enabled by reaction with N3SiMe3. Based on these results, a photocatalytic protocol for aldehyde C?H trimethylsilylamidation was developed that exhibits inverted, nucleophilic selectivity as compared to typical nitrene transfer catalysis. This first example of catalytic C?H nitrogen atom transfer offers facile access to primary amides after deprotection.
Phosphinoferrocene ureas: Synthesis, structural characterization, and catalytic use in palladium-catalyzed cyanation of aryl bromides
?koch, Karel,Císa?ová, Ivana,?těpni?ka, Petr
, p. 1942 - 1956 (2015/06/08)
Phosphinoferrocene ureas Ph2PfcCH2NHCONR2, where NR2 = NH2 (1a), NHMe (1b), NMe2 (1c), NHCy (1d), and NHPh (1e); the analogous thiourea Ph2PfcCH2NHCSNHPh (1f); and the acetamido derivative Ph2PfcCH2NHCOMe (1g) (Cy = cyclohexyl, fc = ferrocene-1,1′-diyl) were prepared via three different approaches starting from Ph2PfcCH2NH2·HCl (3·HCl) or Ph2PfcCHO (4). The reactions of the representative ligand 1e with [PdCl2(cod)] (cod = cycloocta-1,5-diene) afforded [PdCl(μ-Cl)(1e-κP)2]2 or [PdCl2(1e-κP)2]2 depending on the metal-to-ligand stoichiometry, whereas those with [PdCl(η3-C3H5)]2 and [PdCl(LNC)]2 produced the respective bridge cleavage products, [PdCl(η3-C3H5)(1e-κP)] and [PdCl(LNC)(1e-κP)] (LNC = [(2-dimethylamino-κN)methyl]phenyl-κC1). Attempts to involve the polar pendant in coordination to the Pd(II) center were unsuccessful, indicating that the phosphinoferrocene ureas 1 bind Pd(II) preferentially as modified phosphines rather than bifunctional donors. When combined with palladium(II) acetate, the ligands give rise to active catalysts for Pd-catalyzed cyanation of aryl bromides with potassium hexacyanoferrate(II). Optimization experiments revealed that the best results are obtained in 50% aqueous dioxane with a catalyst generated from 1 mol % of palladium(II) acetate and 2 mol % of 1e in the presence of 1 equiv of Na2CO3 as the base and half molar equivalent of K4[Fe(CN)6]·3H2O. Under such optimized conditions, bromobenzenes bearing electron-donating substituents are cyanated cleanly and rapidly, affording the nitriles in very good to excellent yields. In the case of substrates bearing electron-withdrawing groups, however, the cyanation is complicated by the hydrolysis of the formed nitriles to the respective amides, which reduces the yield of the desired primary product. Amine- and nitro-substituted substrates are cyanated only to a negligible extent, the former due to their metal-scavenging ability.
A general and practical oxidation of alcohols to primary amides under metal-free conditions
Wu, Xiao-Feng,Sharif, Muhammad,Feng, Jian-Bo,Neumann, Helfried,Pews-Davtyan, Anahit,Langer, Peter,Beller, Matthias
, p. 1956 - 1961 (2013/09/24)
A general procedure for oxidation of both benzyl alcohols and alkyl alcohols to primary amides under catalyst free conditions has been developed. 34 examples of primary amides were produced from their corresponding alcohols in moderate to excellent yields. This is a practical procedure for primary amides synthesis; water and tert-butanol are the only by-products. A commercial drug, Piracetam, was prepared in one step with 73% yield as well.
