3326-13-4Relevant academic research and scientific papers
Mild, Metal-Free and Protection-Free Transamidation of N-Acyl-2-piperidones to Amino Acids, Amino Alcohols and Aliphatic Amines and Esterification of N-Acyl-2-piperidones
Subramani, Muthuraman,Rajendran, Saravana Kumar
supporting information, p. 3677 - 3686 (2019/06/08)
Amides are indispensable building blocks of biological systems, pharmaceuticals, and materials. We report a highly selective method for the synthesis of amides via transamidation process. Transamidation of N-acyl-2-piperidones with a broad range of amines is demonstrated under exceedingly mild and metal-free reaction condition that relies on the amide bond twist to weaken the amidic resonance. Transamidation proceeds under the neat condition at room temperature, in short reaction times (30–90 min) with good yields. Considerable variation is tolerated with both amine and imide substrates. Of note, amines bearing carboxylic acids (glycine and serine) and hydroxyl groups (dopamine, tyramine, etc.) are well tolerated which are otherwise problematic under the metal-catalyzed protocol. Our current method is applicable for transamidation of both alkyl and aryl-N-acyl-2-piperidones. The practical value of the method is highlighted by the synthesis of four natural product amide alkaloids in high yields under mild reaction conditions. In the absence of nucleophilic amines, N-acyl-2-piperidones undergoes esterification with EtOH at elevated temperature. Single crystal X-ray analysis of an N-acyl-2-piperidone shows amide bond twist, τ = –20.39° and pyramidalization, χN = –11.73°. This weakens the amidic conjugation and might be the factor controlling the reactivity and selectivity of these imides. We envision that the N-acyl-2-piperidone scaffold would be useful in the synthesis of pharmaceuticals and materials.
Oxidative transformation of cyclic ethers/amines to lactones/lactams using a DIB/TBHP protocol
Zhao, Yi,Ang, Jascelyn Qian Lin,Ng, Angela Wan Ting,Yeung, Ying-Yeung
, p. 19765 - 19768 (2013/11/06)
A novel C-H oxidation of cyclic ethers and amines to the corresponding lactones and lactams was developed using a DIB/TBHP protocol. The reaction is mild and no metallic reagent is involved. In addition, study shows that the electronic properties of the substituents could affect the selectivity of oxidation. The Royal Society of Chemistry 2013.
NHC-Catalyzed intramolecular redox amidation for the synthesis of functionalized lactams
Thai, Karen,Wang, Li,Dudding, Travis,Bilodeau, Francois,Gravel, Michel
, p. 5708 - 5711 (2011/03/19)
A very efficient NHC-catalyzed lactamization reaction is reported. For most cases, the ring expansion reaction proceeds to cleanly furnish five- and six-membered N-Ts and N-Bn lactams, without the need for further purification. Evidence is presented suggesting a dual role for the stoichiometric base: (1) deprotonation of the triazolium precatalyst and (2) activation of the nitrogen leaving group through hydrogen bonding.
Toward Transition Metal-Catalyzed Carbonylation of Methanol without HI as Copromoter: Catalytic Exocyclic Carbonylation of Cycloimino Esters
Xu, Hongyu,Jia, Li
, p. 3955 - 3957 (2007/10/03)
(Formula presented). Initial studies of a rare exocyclic C-O bond carbonylation are reported. Under the catalysis of Co2(CO) 8 in the absence of HI as the copromoter, cycloimino esters are carbonylated to afford N-acyllactams in high yields under relatively mild conditions (100-160°C and 200-1000 psi). The reaction is interesting because it opens up the possibility of carbonylation of alcohols in the absence of HI.
Aerobic oxidation of N-alkylamides catalyzed by N-hydroxyphthalimide under mild conditions. Polar and enthalpic effects
Minisci, Francesco,Punta, Carlo,Recupero, Francesco,Fontana, Francesca,Franco Pedulli, Gian
, p. 2671 - 2676 (2007/10/03)
The oxidation of N-alkylamides by O2, catalyzed by N-hydroxyphthalimide (NHPI) and Co(II) salt, leads under mild conditions to carbonyl derivatives (aldehydes, ketones, carboxylic acids, imides) whose distribution depends on the nature of the alkyl group and on the reaction conditions. Primary N-benzylamides lead to imides and aromatic aldehydes at room temperature without any appreciable amount of carboxylic acids, while under the same conditions nonbenzylic derivatives give carboxylic acids and imides with no trace of aldehydes, even at very low conversion. These results are explained through hydrogen abstraction by the phthalimide-N-oxyl (PINO) radical, whose reactivity with benzyl derivatives is governed by polar effects, so that benzylamides are much more reactive than the corresponding aldehydes. The enthalpic effect is, however, dominant with nonbenzylic amides, making the corresponding aldehydes much more reactive than the starting amides. The importance of the bond dissociation energy (BDE) of the O-H bond in NHPI is emphasized.
Asymmetric synthesis of novel quaternary α-hydroxy-δ-lactam dipeptide surrogates
Minami, Nathaniel K.,Reiner, John E.,Semple, J. Edward
, p. 2625 - 2628 (2007/10/03)
Application of the Sharpless AD protocol to a series of α-(E)-benzylidene-δ-lactam precursors followed by selective deoxygenation provided efficient synthetic routes to the chiral quaternary α-hydroxy-γ-lactam derivatives 4 and 5. These functionalized intermediates and the diol precursors 3 are regarded as novel types of D-Phe-Pro dipeptide surrogates that are useful as enzyme active site probes.
Mild Acetylation of Amides, Thiamides, Ureas, and Thioureas Using Methyl Bis(1-naphthyl)bismuthinate in Acetic Acid
Ogawa, Takuji,Miyazaki, Kikuko,Suzuki, Hitomi
, p. 1651 - 1654 (2007/10/02)
Amides, thioamides, ureas, and thioureas were N-acetylated in good yield with acetic acid in the presence of methyl bis(1-naphthyl)bismuthinate at room tempereature.
