3027-02-9Relevant articles and documents
Hydrosilane Reduction of Nitriles to Primary Amines by Cobalt-Isocyanide Catalysts
Sanagawa, Atsushi,Nagashima, Hideo
supporting information, p. 287 - 291 (2019/01/10)
Reduction of nitriles to silylated primary amines was achieved by combination of 1,1,3,3-tetramethyldisiloxane (TMDS) as the hydrosilane and a catalytic amount of Co(OPIV)2 (PIV = COtBu) associated with isocyanide ligands. The resulting silylated amines were subjected to acid hydrolysis or treatment with acid chlorides to give the corresponding primary amines or imides in good yields. One-pot synthesis of primary amides to primary amines with hydrosilanes was also achieved by iron-cobalt dual catalyst systems.
Steric and Electronic Effects in the Synthesis and Regioselective Hydrolysis of Unsymmetrical Imides
Shang, Jing,Pourvali, Aysa,Cochrane, James R.,Hutton, Craig A.
, p. 1854 - 1858 (2015/12/26)
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.
A new method for peptide synthesis in the N→C direction: Amide assembly through silver-promoted reaction of thioamides
Pourvali, Aysa,Cochrane, James R.,Hutton, Craig A.
, p. 15963 - 15966 (2015/01/09)
The Ag(i)-promoted coupling of amino acids and peptides with amino ester thioamides generates peptide imides without epimerisation. The peptide imides undergo regioselective hydrolysis under mild conditions to generate native peptides. This method was employed to prepare the pentapeptide thymopentin in the N→C direction, in high yield and purity.
Reaction of essentially free benzyl cations with acetonitrile; synthesis of ethanimidic carboxylic anhydrides and unsymmetrical diacylamines
Darbeau, Ron W.,White, Emil H.,Nunez, Nicholas,Coit, Brian,Daigle, Mark
, p. 1115 - 1120 (2007/10/03)
Benzyl cations were generated via the thermal decomposition of N-benzyl- N-nitrosopivalamide in acetonitrile and acetonitrile-water mixtures at 25 °C. The first-formed (primary) benzylating agent, the benzyl cation, was scavenged competitively by pivalate (trimethyl acetate) ion to yield benzyl pivalate, by acetonitrile to yield the corresponding N-benzylnitrilium ion, and by water (when present) to yield benzyl alcohol. The nitrilium ion underwent a cascade of reactions to yield an array of products whose identities and relative yields as a function of time were used to elucidate the mechanistic paths involved. Thus, the N-benzylnitrilium ion reacted with pivalate ion to yield the Z-isomer of N-benzylethanimidic pivalic anhydride, followed by its conversion into the E-isomer. This article appears to be the first to document compounds of this type. The E-isomer is labile under the reaction conditions, rearranging into N-acetyl-N-pivalylbenzylamine. In the presence of water as a diluent, a significant fraction of the nitrosoamide was hydrolyzed to benzyl alcohol; hydrolysis of the nitrilium ion yielded N- benzyl acetamide. The yield of hydrosylates was directly proportional to the mole fraction of water in the medium.
Gas-phase kinetics of N-substituted diacetamide
Al-Awadi,Al-Omran
, p. 951 - 954 (2007/10/03)
Gas-phase elimination reactions of number of N-substituted diacetamides have been studied. The rates of N-phenyl, 4-methoxyphenyl, 4-nitrophenyl, and benzyl diacetamide have been measured between 643-683, 642-693, 673-725, and 555-610 K, respectively. They undergo unimolecular first-order elimination reactions, for which log A = 12.8, 12.9, 12.8, and 11.0 s-1 and Ea = 185.7, 191.4, 193.4, and 143.6 kJ mol-1, respectively. The reactivity of these compounds has been compared with the unsubstituted diacetamide at 600 K. The kinetic data reveals that each of the N-aryldiacetamides is less reactive than the parent molecule. We attribute this observation to the resonance of the lone pair of electrons on the nitrogen with either the two carbonyl oxygen atoms or with the 6π electrons in the aromatic ring which will result in the stabilization of the N-aryldiacetamides related to the parent molecules.
Acyl Trimethylsilyl Polyphosphates as Activated Esters in Acylation Reactions
Rao, C. Someswara,Rambabu, M.,Srinivasan, P. S.
, p. 407 - 411 (2007/10/02)
The preparation and application of a new class of activated esters, acyl trimethylsilyl polyphosphates, are described.These complexes, prepared by the reaction of trimethylsilyl carboxylates with phosphorus pentoxide, are versatile acylating agents under relatively mild conditions.Sodium or potassium halides and imidazole are very effective catalysts leading to the in situ generation of reactive acyl halides and acyl imidazolides.Amines, amides, alcohols and phenols, p-thiocresol, carboxylic acids and trimethylsilyl carboxylates, and hexamethyldisilazane have been acylated to give high yields of amides, imides, esters, thioesters, anhydrides and nitriles, respectively.
