- Metal-free reductive cleavage of N-O bonds in weinreb amides by an organic neutral super-electron donor
-
The scope of neutral organic super-electron donors as reducing agents has been extended to include the reductive cleavage of N-O bonds in Weinreb amides. This methodology proved to be applicable to a large array of substrates to afford their reduced counterparts in good to excellent yields. The variation in reactivity within the set of tested amides is rationalised. Georg Thieme Verlag Stuttgart.
- Cutulic, Sylvain P. Y.,Murphy, John A.,Farwaha, Hardeep,Zhou, Sheng-Ze,Chrystal, Ewan
-
-
Read Online
- Tandem Transformation of Aldoximes to N-Methylated Amides Using Methanol
-
Tandem conversion of aldoximes to N-methylated amides with methanol in presence of a single Ru(II) catalyst is accomplished through the Ru(II)-mediated rearrangement followed by the reductive N-methylation. Employing this protocol, several aldoximes were directly transformed to the N-methylated amides using methanol. Kinetic experiments with H218O advocated that the aldoxime is acted as the nucleophile during the aldoxime to amide rearrangement process. Involvement of nitrile intermediate during this transformation is realized from the kinetic study. (Figure presented.).
- Paul, Bhaskar,Maji, Milan,Panja, Dibyajyoti,Kundu, Sabuj
-
-
Read Online
- Mechanistic insights into the: In vitro metal-promoted oxidation of (di)azine hydroxamic acids: Evidence of HNO release and N, O -di(di)azinoyl hydroxylamine intermediate
-
The oxidant-dependent ability of hydroxamic acids to release nitroxyl (HNO), a small inorganic molecule endowed with various biological properties, is addressed from a mechanistic standpoint. Indeed, the exact mechanism of the hydroxamic acid oxidation in physiological conditions and the direct or indirect characterization of the intermediates remain elusive. In this work, intermolecular oxidation of isonicotino-, nicotino- and pyrazino-hydroxamic acids with K3[FeIII(CN)6] at physiological pH (7.4), was monitored by 1H NMR, MS, EPR and UV-vis techniques. While nitrosocarbonyl (di)azine intermediates, (di)Az-C(O)-NO, could be a priori envisaged, it was in fact the corresponding N,O-di(di)azinoylhydroxylamines (AzC(O)NHOC(O)Az) and HNO that were identified, the first by 1H NMR and the second on the basis of EPR and UV-vis experiments using the [2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide] (cPTIO) spin trap. The decomposition of the unstable N,O-di(di)azinoylhydroxylamine intermediates in aqueous buffer media was shown to generate the corresponding carboxylic acids as final organic products, envisaged as possible in vivo metabolites. The same oxidation experiments performed in the presence of methylamine led to the corresponding N-methyl amides suggesting that, unlike hydroxamic acids, N,O-di(di)azinoylhydroxylamines act as acylating agents in physiological pH conditions.
- Carvalho, Edinilton Muniz,Rechignat, Lionel,Sousa, Eduardo Henrique Silva De,Lopes, Luiz Gonzaga De Fran?a,Chauvin, Remi,Bernardes-Génisson, Vania
-
-
Read Online
- Preparation method of racemic nicotine
-
The invention discloses a preparation method of racemic nicotine. The method comprises the following steps of: preparing methyl nicotinamide from nicotinoyl chloride and methylamine under alkaline conditions; condensing the methyl nicotinamide with monochloroacetone to obtain N-methyl-N-(2-oxypropyl) nicotinamide; carrying out aldol condensation reaction on theN-methyl-N-(2-oxypropyl) nicotinamide to obtain 1-methyl-5-(pyridine-3-yl)-1, 2-dihydro-3H-pyrrole-3-ketone; and finally performing reduction to obtain the racemic nicotine. The invention provides a new route for synthesizing the racemic nicotine; the cheap and easily available nicotinoyl chloride and methylamine are adopted as starting raw materials, so that the cost of the raw materials is low; the whole reaction synthesis route is relatively short, the operation is simple, the reaction condition is mild, the post-treatment is simple; the yield of the synthesized racemic nicotine is high; and the method is suitable for industrial large-scale production.
- -
-
Paragraph 0048-0056
(2021/10/30)
-
- Dealkoxylation ofN-alkoxyamides without an external reductant driven by Pd/Al cooperative catalysis
-
Lewis acid-assisted palladium-catalysed dealkoxylation ofN-alkoxyamides has been developed. This reaction proceeded smoothly with a range ofN-alkoxyamides in the absence of an external reductant, thereby establishing a convenient and reductant-free protocol. In addition, a gram-scale reaction could be achieved. Preliminary mechanistic investigations indicated that β-hydrogen elimination from a palladium alkoxide intermediate generated an intramolecular hydride source.
- Suzuki, Hirotsugu,Shiomi, Takahiro,Yoneoka, Kenji,Matsuda, Takanori
-
supporting information
p. 7545 - 7548
(2020/10/15)
-
- Chemoselective Synthesis of Aryl Ketones from Amides and Grignard Reagents via C(O)-N Bond Cleavage under Catalyst-Free Conditions
-
Conversion of a wide range of N-Boc amides to aryl ketones was achieved with Grignard reagents via chemoselective C(O)-N bond cleavage. The reactions proceeded under catalyst-free conditions with different aryl, alkyl, and alkynyl Grignard reagents. α-Ketoamide was successfully converted to aryl diketones, while α,β-unsaturated amide underwent 1,4-addition followed by C(O)-N bond cleavage to provide diaryl propiophenones. N-Boc amides displayed higher reactivity than Weinreb amides with Grignard reagents. A broad substrate scope, excellent yields, and quick conversion are important features of this methodology.
- Sureshbabu, Popuri,Azeez, Sadaf,Muniyappan, Nalluchamy,Sabiah, Shahulhameed,Kandasamy, Jeyakumar
-
p. 11823 - 11838
(2019/10/02)
-
- Ruthenium-Catalyzed Synthesis of N-Methylated Amides using Methanol
-
An efficient synthesis of N-methylated amides using methanol in the presence of a ruthenium(II) catalyst is realized. Notably, applying this process, tandem C-methylation and N-methylation were achieved to synthesize α-methyl N-methylated amides. In addition, several kinetic studies and control experiments with the plausible intermediates were performed to understand this novel protocol. Furthermore, detailed computational studies were carried out to understand the mechanism of this transformation.
- Paul, Bhaskar,Panja, Dibyajyoti,Kundu, Sabuj
-
supporting information
p. 5843 - 5847
(2019/08/26)
-
- Atom-Economical and Tandem Conversion of Nitriles to N-Methylated Amides Using Methanol and Water
-
A cobalt complex catalyzed tandem conversion of nitrile to N-methylated amide is described using a methanol and water mixture. Using this protocol, several nitriles were directly and efficiently converted to the desired N-methylated amides. Kinetic experiments using H2O18 and CD3OD suggested that water and methanol were the source of the oxygen atom and methyl group, respectively, in the final N-methylated amides. Importantly, the participation of active Co(I)-H species in this transformation was realized from the control experiment. The kinetic isotope effect (KIE) study suggested that the activation of the C-H bond of methanol was a kinetically important step. The Hammett plot confirmed that the reaction was faster with the electron deficient nitriles. In addition, the plausible pathway for the formation of N-methylated amides from the nitriles was supported by the computational study.
- Paul, Bhaskar,Maji, Milan,Kundu, Sabuj
-
p. 10469 - 10476
(2019/11/05)
-
- Silica-supported 2,4,6-trichloro-1,3,5-triazine as an efficient reagent for direct conversion of carboxylic acids to amides under solvent-free conditions
-
A very simple and efficient solvent-free method for the direct conversion of carboxylic acids to primary, secondary, tertiary alkyl, and aromatic amides in the presence of the corresponding ammonium salts, silica-supported 2,4,6-trichloro-1,3,5-triazine, and triethylamine is described. The reactions proceed rapidly at room temperature, and the products are obtained in moderate to excellent yields. Copyright Taylor & Francis Group, LLC.
- Khalafi-Nezhad, Ali,Zare, Abdolkarim,Parhami, Abolfath,Rad, Mohammad Navid Soltani,Nejabat, Gholam Reza
-
p. 657 - 666
(2008/09/21)
-
- Efficient method for the direct preparation of amides from carboxylic acids using tosyl chloride under solvent-free conditions
-
A simple, clean and highly efficient solvent-free procedure for the preparation of primary, secondary, tertiary and aromatic amides is described from the direct reaction of carboxylic acids and silica-supported ammonium salts, triethylamine (TEA) and tosyl chloride (TsCl) as condensing agent. The reaction proceeds rapidly in high yields at room temperature.
- Khalafi-Nezhad, Ali,Parhami, Abolfath,Soltani Rad, Mohammad Navid,Zarea, Abdolkarim
-
p. 6879 - 6882
(2007/10/03)
-
- AN ALTERNATIVE PROCEDURE FOR THE ALUMINUM-MEDIATED CONVERSION OF ESTERS TO AMIDES
-
A convenient method has been developed for directly converting esters to amides using reagents derived from the reaction of trimethylaluminum with ammonium chloride, methylamine hydrochloride or dimethylamine hydrochloride.
- Levin, Jeremy I.,Turos, Edward,Weinreb, Steven M.
-
p. 989 - 994
(2007/10/02)
-