- Acyl and Decarbonylative Suzuki Coupling of N-Acetyl Amides: Electronic Tuning of Twisted, Acyclic Amides in Catalytic Carbon-Nitrogen Bond Cleavage
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We report the Pd-catalyzed acyl and the Ni-catalyzed biaryl Suzuki-Miyaura cross-coupling of N-acetyl-amides with arylboronic acids by selective N-C(O) cleavage. Activation of the amide bond by N-acylation provides electronically destabilized, acyclic, nonplanar amide, which readily undergoes cross-coupling with a wide range of boronic acids to produce biaryl ketones or biaryls in a highly efficient manner. Most crucially, the presented results introduce N-acetyl-amides as reactive acyclic amides in the emerging manifold of transition-metal-catalyzed amide cross-coupling. The scope and origin of high selectivity are discussed. Mechanistic studies point to remodeling of amidic resonance and amide bond twist as selectivity determining features in a unified strategy for cross-coupling of acyclic amides. Structural studies, mechanistic investigations as well as beneficial effects of the N-acyl substitution on cross-coupling of amides are reported.
- Liu, Chengwei,Li, Guangchen,Shi, Shicheng,Meng, Guangrong,Lalancette, Roger,Szostak, Roman,Szostak, Michal
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- Nickel-Catalyzed Phosphine Free Direct N-Alkylation of Amides with Alcohols
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Herein, we developed an operational simple, practical, and selective Ni-catalyzed synthesis of secondary amides. Application of renewable alcohols, earth-abundant and nonprecious nickel catalyst facilitates the transformations, releasing water as byproduct. The catalytic system is tolerant to a variety of functional groups including nitrile, allylic ether, and alkene and could be extended to the synthesis of bis-amide, antiemetic drug Tigan, and dopamine D2 receptor antagonist Itopride. Preliminary mechanistic studies revealed the participation of a benzylic C-H bond in the rate-determining step.
- Das, Jagadish,Banerjee, Debasis
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p. 3378 - 3384
(2018/03/26)
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- Steric and Electronic Effects in the Synthesis and Regioselective Hydrolysis of Unsymmetrical Imides
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The AgI-promoted coupling reaction of thioamides and carboxylic acids is shown to be a useful method for the generation of unsymmetrical imides. The reaction proceeds efficiently with unhindered and electron-rich or neutral coupling partners, but not with hindered thioamides (such as thiopivalamides) or electron deficient thioamides (such as trifluorothioacetamides). Intriguingly, thioformamides are also ineffective coupling partners, despite having minimal steric or electronic influence. Hindered carboxylic acid coupling partners (such as pivalic acid) are tolerated, but electron deficient acids, such as trifluoroacetic acid, are ineffective coupling partners. Furthermore, an interplay of both steric and electronic effects is observed in the subsequent hydrolysis of unsymmetrical imides. Imides with a dimethoxybenzoyl group give high regioselectivity upon hydrolysis, favouring cleavage of the distal acyl group. Imides with a p-nitrobenzoyl or pivaloyl group give reversed selectivity, favouring cleavage of the proximal acyl group.
- Shang, Jing,Pourvali, Aysa,Cochrane, James R.,Hutton, Craig A.
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p. 1854 - 1858
(2015/12/26)
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- Fe-Catalysed oxidative C-H/N-H coupling between aldehydes and simple amides
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A novel oxidative coupling of aldehydes with simple amides, most likely involving a radical process, was achieved through the use of an iron catalyst. Various amides were utilized as substrates to easily construct imides by coupling with aldehydes. A catalytic cycle involving the benzoyl halide intermediate is proposed based on our experimental results. This journal is the Partner Organisations 2014.
- Wang, Jing,Liu, Chao,Yuan, Jiwen,Lei, Aiwen
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supporting information
p. 4736 - 4739
(2014/05/06)
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- Acyclic ketene aminal phosphates derived from N,N-diprotected acetamides: stability and cross-couplings
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The synthesis of a stable ketene aminal phosphate (α-phosphoryloxy enecarbamate) derived from N,N-diprotected acetamide, bearing two different removable protecting groups, is disclosed. This synthetic intermediate underwent successful palladium-catalyzed cross-coupling reactions to afford functionalized enynes and dienes.
- Simas, Alessandro B.C.,de Sales, Daniel L.,Pais, Karla C.
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experimental part
p. 6977 - 6980
(2010/02/27)
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- The Darbeau-White-Gibble reaction: An N-nitrosoamide-mediated Ritter-type reaction. Part I. A study of electronic, steric, and orbital effects in the nucleophile1a
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Benzyl cations were generated via thermal decomposition of N-benzyl-N-nitrosopivalamide in molten 4-R-substituted benzonitriles (R = NH2, Me2N, MeO, Me, H, F, and CF3). In each case, the benzyl cation was intercepted competitively by pivalate ion to yield benzyl pivalate and by the benzonitriles to yield the corresponding N-4-R-benzonitrilium ion. The latter onium ions reacted with pivalate ion to form benzimidic anhydrides which rearranged to yield N-4-R-benzoyl-N-pivaloylbenzylamines (i.e. unsymmetrical diacylamines). The yield of diacylamines (maximum ~10.6% for R = H) is smaller than from the corresponding reactions in acetonitrile and varied systematically with the nature and location of the R group on the aromatic nucleus. Both electron-releasing and electron-withdrawing groups at the para position effected a diminution of the yield of diacylamine; indeed for R = NH2, no diacylamine was formed. ortho Substitution of the aromatic nucleus resulted in significantly diminished yields of diacylamine, as did nucleophilic attack on the nitrilium ion by pivalate rather than acetate. Thus, both electronic and steric effects in nucleophilic attack on the nitrilium carbon were observed. The ratios of counterion-derived product to solvent-derived product for both the first-formed benzyl cation and the less reactive benzonitrilium ion are similar. This observation is interpreted in terms of the intermediacy of nitrogenous entity-separated ion-pairs in these deaminations.
- Darbeau,Gibble,Pease,Bridges,Siso,Heurtin
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p. 1084 - 1090
(2007/10/03)
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- Asymmetric synthesis of β-amino acids by addition of chiral enolates to nitrones via N-acyloxyiminium ions
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N-Acyloxyiminium ions, generated by the reaction of nitrones with acyl halides, are highly reactive species and undergo facile reaction with a wide range of nucleophiles, such as ketene silyl acetals, titanium(IV) and boron enolates, hydrido- and allyltin(IV) reagents, and alkynyltitanium(IV) reagents, to give α-substituted amine derivatives. Optically active β-amino acids can be prepared by the reaction of N-acyloxyiminium ions with both boron and titanium(IV) enolates bearing chiral auxiliaries. Reversal of diastereoselectivity was observed by the reactions of the boron and titanium(IV) enolates. Using these reactions, all of the four stereoisomers of α-methyl-β-phenylalanines, for example, can be prepared highly diastereoselectively. Cyclic N-acyloxyiminium ions are useful for the asymmetric synthesis of pyrrolidine and piperidine alkaloids; (5R,8R,8aS)-5-cyano-8-methylindolizidine, which is a common key intermediate for synthesis of 5-substituted 8-methylindolizidines, was prepared selectively.
- Kawakami,Ohtake,Arakawa,Okachi,Imada,Murahashi
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p. 2423 - 2444
(2007/10/03)
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- Reaction of nitrones with trimethylsilyiketene
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Trimethylsilylketene smoothly reacts with α,N-diarylnitrones to give oxindoles in good yields. On the other hand, the reaction of trimethylsilylketene with N-arylmethylnitrones gives a mixture of N,N- diacylamines and N-acylamines.
- Takaoka, Kiyo,Aoyama, Toyohiko,Shioiri, Takayuki
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p. 3017 - 3020
(2007/10/03)
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- FACILE METHOD FOR THE ACYLATION OF ALCOHOLS AND AMIDES BY THE USE OF 1,1'-DIMETHYLSTANNOCENE AND ACYL CHLORIDES
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Acylation of alcohols and amides was effected under mild conditions by the use of 1,1'-dimethylstannocene and acyl chlorides, giving the corresponding esters and imides in good to excellent yields.
- Mukaiyama, Teruaki,Ichikawa, Junji,Asami, Masatoshi
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p. 293 - 296
(2007/10/02)
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