1523-19-9Relevant articles and documents
Mechanically induced solvent-free esterification method at room temperature
Zheng, Lei,Sun, Chen,Xu, Wenhao,Dushkin, Alexandr V.,Polyakov, Nikolay,Su, Weike,Yu, Jingbo
, p. 5080 - 5085 (2021/02/05)
Herein, we describe two novel strategies for the synthesis of esters, as achieved under high-speed ball-milling (HSBM) conditions at room temperature. In the presence of I2 and KH2PO2, the reactions afford the desired esterification derivatives in 45% to 91% yields within 20 min of grinding. Meanwhile, using KI and P(OEt)3, esterification products can be obtained in 24% to 85% yields after 60 min of grinding. In addition, the I2/KH2PO2 protocol was successfully extended to the late-stage diversification of natural products showing the robustness of this useful approach. Further application of this method in the synthesis of inositol nicotinate was also discussed. This journal is
Metal-Free Selective Modification of Secondary Amides: Application in Late-Stage Diversification of Peptides
Adebomi, Victor,Sriram, Mahesh,Streety, Xavier,Raj, Monika
supporting information, p. 6189 - 6193 (2021/08/01)
Here we solve a long-standing challenge of the site-selective modification of secondary amides and present a simple two-step, metal-free approach to selectively modify a particular secondary amide in molecules containing multiple primary and secondary amides. Density functional theory (DFT) provides insight into the activation of C-N bonds. This study encompasses distinct chemical advances for late-stage modification of peptides thus harnessing the amides for the incorporation of various functional groups into natural and synthetic molecules.
Preparation of Carbamates, Esters, Amides, and Unsymmetrical Ureas via Br?nsted Acid-Activated N-Acyl Imidazoliums
Watson, Rebecca B.,Butler, Todd W.,Deforest, Jacob C.
supporting information, p. 500 - 506 (2021/01/09)
We report the application of Br?nsted acid-activated N-acyl imidazoliums as versatile intermediates in carbonyl transformations. The efficient and scalable procedure was validated on a diverse set of carbamates, esters, amides, and unsymmetrical ureas (21 examples, up to 91% yield). Additionally, we exemplify this method on multikilogram scale for the synthesis of an electron-deficient carbamate.
Hydrogen-bond-assisted transition-metal-free catalytic transformation of amides to esters
Huang, Changyu,Li, Jinpeng,Wang, Jiaquan,Zheng, Qingshu,Li, Zhenhua,Tu, Tao
, p. 66 - 71 (2020/11/18)
The amide C-N cleavage has drawn a broad interest in synthetic chemistry, biological process and pharmaceutical industry. Transition-metal, luxury ligand or excess base were always vital to the transformation. Here, we developed a transition-metal-free hydrogen-bond-assisted esterification of amides with only catalytic amount of base. The proposed crucial role of hydrogen bonding for assisting esterification was supported by control experiments, density functional theory (DFT) calculations and kinetic studies. Besides broad substrate scopes and excellent functional groups tolerance, this base-catalyzed protocol complements the conventional transition-metal-catalyzed esterification of amides and provides a new pathway to catalytic cleavage of amide C-N bonds for organic synthesis and pharmaceutical industry. [Figure not available: see fulltext.]
Carboxylic Acid Deoxyfluorination and One-Pot Amide Bond Formation Using Pentafluoropyridine (PFP)
Brittain, William D. G.,Cobb, Steven L.
, p. 5793 - 5798 (2021/08/01)
This work describes the application of pentafluoropyridine (PFP), a cheap commercially available reagent, in the deoxyfluorination of carboxylic acids to acyl fluorides. The acyl fluorides can be formed from a range of acids under mild conditions. We also demonstrate that PFP can be utilized in a one-pot amide bond formation via in situ generation of acyl fluorides. This one-pot deoxyfluorination amide bond-forming reaction gives ready access to amides in yields of ≤94%.
Photo-Fries rearrangement in flow under aqueous micellar conditions
Chen, Chun-Jen,Chien, Chia-Chen,Kao, Shih-Chieh,Wu, Yen-Ku
supporting information, p. 15470 - 15472 (2020/12/25)
A flow edition of photo-Fries rearrangement for the synthesis of 2-acylphenols in an aqueous micellar medium has been described. We take advantage of a narrow channel reactor and micelle-induced confinement effect to refine both the efficiency and selectivity of the parent photoreaction. This journal is
Nucleophilic aromatic substitution of unactivated fluoroarenes enabled by organic photoredox catalysis
Nicewicz, David A.,Pistritto, Vincent A.,Schutzbach-Horton, Megan E.
supporting information, p. 17187 - 17194 (2020/11/02)
Nucleophilic aromatic substitution (SNAr) is a classical reaction with well-known reactivity toward electron-poor fluoroarenes. However, electron-neutral and electron-rich fluoro(hetero)arenes are considerably underrepresented. Herein, we present a method for the nucleophilic defluorination of unactivated fluoroarenes enabled by cation radical-accelerated nucleophilic aromatic substitution. The use of organic photoredox catalysis renders this method operationally simple under mild conditions and is amenable to various nucleophile classes, including azoles, amines, and carboxylic acids. Select fluorinated heterocycles can be functionalized using this method. In addition, the late-stage functionalization of pharmaceuticals is also presented. Computational studies demonstrate that the site selectivity of the reaction is dictated by arene electronics.
Visible light-mediated transition metal-free esterification of amides with boronic acids
Ding, Hao,Qi, Wan-Ying,Zhen, Jing-Song,Ding, Qiuping,Luo, Yong
supporting information, (2020/10/02)
A novel strategy for visible light-mediated esterification of amides with boronic acids in air has been described. This method is characterized by mild reaction conditions and low cost owing to no need of any catalyst, which implies high potential utility in late-stage functionalization of amide drugs and materials.
Palladium-catalyzed aryloxy- and alkoxycarbonylation of aromatic iodides in γ-valerolactone as bio-based solvent
Tukacs, József M.,Marton, Bálint,Albert, Eszter,Tóth, Imre,Mika, László T.
, (2020/08/11)
Fossil-based solvents and triethylamine as a toxic and volatile base were successfully replaced with γ-valerolactone as a non-volatile solvent and K2CO3 as inorganic base in the alkoxy- and aryloxycarbonylation of aryl iodides using phosphine-free Pd catalyst systems. By this, the traditional systems were not simply replaced but also significantly improved. In the study, the effects of different reaction parameters, i.e. the use of several other solvents, the temperature, the carbon monoxide pressure, the base and the catalyst concentrations, were evaluated in details on the efficiency of the carbonylations. To gather some information on the mechanism of these reactions, the effects of the electronic parameters (σ) of various aromatic substituents of the aryl iodides as well as the influence of para-substitution of phenol were investigated on the activity. For a comparison, the aryl-substituted aryl iodides were also reacted with methanol and aryl iodide was also alkoxycarbonylated using several different lower alcohols. From the observed correlations between the electronic parameters of the aromatic substituents and the rates, it appears that the rate determining step is the oxidative addition of Ar–I to Pd0, provided that sufficient amounts of nucleophiles are present for the ester formation. If this is not the case, the rate of nucleophile attack might determine the overall rate.
