1004-10-0Relevant articles and documents
CID fragmentation of deprotonated N-Acyl aromatic sulfonamides. Smiles-type and nitrogen-oxygen rearrangements
Liang, Yuxue,Simón-Manso, Yamil,Neta, Pedatsur,Yang, Xiaoyu,Stein, Stephen E.
, p. 806 - 814 (2021)
The NIST tandem mass spectral library (2020 version) includes over 800 aromatic sulfonamides. In negative mode, upon collisional activation most benzenesulfonamides lose a neutral SO2 molecule leading to an anilide anion (C6H5NH-, m/z 92). However, for deprotonated N-benzoyl aromatic sulfonamides, the phenoxide ion (C6H5O-, m/z 93.0343) is the principal product ion. A variety of N-acylbenzenesulfonamide derivatives were also found to overwhelmingly produce the phenoxide ion as the most intense product ion. A mechanism is proposed in which, at low energy, a carbonyl oxygen atom (C=O) is transferred to a benzene ring, known as a Smiles-type rearrangement (the amide oxygen atom attacks the arylsulfonyl group at the ipso position), in parallel and determining the reaction at high energy a nitrogen-oxygen rearrangement mechanism leads to the formation of the phenoxide ion. Tandem mass spectra of deprotonated N-benzoyl-18O-benzenesulfonamide and N-thiobenzoyl-p-toluenesulfonamide confirmed the rearrangement since base peaks at m/z 95.0384 and 123.0270 which correspond to an 18O phenoxide ion ([C6H518O]-) and a 4-methylbenzenethiolate anion ([CH3C6H4S]-) were observed, respectively. The parallel mechanism is supported by the strong correlation between the observed product ion intensities and the corresponding activation energies obtained by Density Functional Theory calculations. This is an example of a relatively simple ion with a complex path to fragmentation, being a cautionary tale for indiscriminate use of in silico spectra in place of actual measurement.
Selective C-C bond cleavage of amides fused to 8-aminoquinoline controlled by a catalyst and an oxidant
Li, Sen,Jie, Kun,Yan, Wenjie,Pan, Qingjun,Zhang, Min,Wang, Yufeng,Fu, Zhengjiang,Guo, Shengmei,Cai, Hu
, p. 13820 - 13823 (2020)
Herein, copper-catalyzed direct C-C bond cleavage of amides fused to 8-aminoquinoline as a directing group to form urea in the presence of amines and dioxygen is reported. Compared to the previous C-H aminations of amides via C-H activation, this reaction presents a catalyst and oxidant controlled C-C bond cleavage strategy that enables amidation through a radical process. CuBr/Ag2CO3/O2 shows the best catalytic result at 150 °C. A series of aryl and alkyl amides were compatible with this transformation. Notably, this method provided access to cyclohexanone, one of the most important industrial materials. The pathway of this reaction was investigated.
Rhodium-Catalyzed Formal C-O Insertion in Carbene/Alkyne Metathesis Reactions: Synthesis of 3-Substituted 3 H-Indol-3-ols
Jia, Shikun,Dong, Guizhi,Ao, Chaoqun,Jiang, Xianxing,Hu, Wenhao
, p. 4322 - 4326 (2019)
An efficient and novel rhodium-catalyzed formal C-O insertion reaction of alkyne-tethered diazo compounds for the synthesis of 3H-indol-3-ols is described. A type of donor/donor rhodium carbene generated in situ via a carbene/alkyne metathesis (CAM) proce
Loss of isotope labeling in the conversion of [18O2]benzoic acid into [18O]benzoyl chloride with oxalyl chloride
Haiss, Peter,Zeller, Klaus-Peter
, p. 303 - 305 (2003)
Tell me where the 18O atoms are, where are they to be found? This question was raised when a large amount of the 18O labeling was lost in the course of the conversion of [18O2]benzoic acid into [18O]b
GC/MSn analysis of the crude reaction mixtures from Friedel–Crafts acylation: Unambiguous identification and differentiation of 3-aroylbenzofurans from their 4- and 6-regioisomers
Begala, Michela,Delogu, Giovanna Lucia,Mancinelli, Michele,Quezada, Elias
, (2021)
Rationale: 3-Aroylbenzofurans and their 2-nitrophenyl derivatives constitute fundamental intermediates for the synthesis of target compounds with pharmaceutical properties. However, their preparation via the Friedel–Crafts acylation of 2-phenylbenzofurans
Fragmentation of Protonated N-(3-Aminophenyl)Benzamide and Its Derivatives in Gas Phase
Zu, Chengli,Mukhopadhyay, Sukrit,Hanley, Patrick S.,Xia, Shijing,Bell, Bruce M.,Grigg, David,Gilbert, Jeffrey R.,O’Brien, John P.
, p. 917 - 926 (2016)
An ion of m/z 110.06036 (ion formula [C6H8NO]+; error: 0.32 mDa) was observed in the collision induced dissociation tandem mass spectrometry experiments of protonated N-(3-aminophenyl)benzamide, which is a rearrangement product ion purportedly through nitrogen-oxygen (N–O) exchange. The N–O exchange rearrangement was confirmed by the MS/MS spectrum of protonated N-(3-aminophenyl)-O18-benzamide, where the rearranged ion, [C6H8NO18]+ of m/z 112 was available because of the presence of O18. Theoretical calculations using Density Functional Theory (DFT) at B3LYP/6-31?g(d) level suggest that an ion-neutral complex containing a water molecule and a nitrilium ion was formed via a transition state (TS-1), followed by the water molecule migrating to the anilide ring, eventually leading to the formation of the rearranged ion of m/z 110. The rearrangement can be generalized to other protonated amide compounds with electron-donating groups at the meta position, such as, –OH, –CH3, –OCH3, –NH(CH3)2, –NH-Ph, and –NHCOCH3, all of which show the corresponding rearranged ions in MS/MS spectra. However, the protonated amide compounds containing electron-withdrawing groups, including –Cl, –Br, –CN, –NO2, and –CF3, at the meta position did not display this type of rearrangement during dissociation. Additionally, effects of various acyl groups on the rearrangement were investigated. It was found that the rearrangement can be enhanced by substitution on the ring of the benzoyl with electron-withdrawing groups. [Figure not available: see fulltext.]
Metal-Free C-H [5 + 1] Carbonylation of 2-Alkenyl/Pyrrolylanilines Using Dioxazolones as Carbonylating Reagents
Nan, Jiang,Chen, Pu,Gong, Xue,Hu, Yan,Ma, Qiong,Wang, Bo,Ma, Yangmin
supporting information, p. 3761 - 3766 (2021/05/10)
A novel metal-free C-H [5 + 1] carbonylative annulation of 2-alkenyl/pyrrolylanilines with dioxazolones has been established for the assembly of the privileged quinolinones and pyrrolyl-fused quinoxalinones. Entirely differing from the existing reports, the dioxazolones herein behave with an innovative chemistry and first emerge as carbonylating reagents to participate in annulation reactions. Moreover, this process features exceedingly simple operation (only solvent) and tolerates both vinyl and aryl substrates. Comprehensive mechanistic studies indicate that the formed isocyanate intermediate plays a crucial role in enabling the carbonylation annulation.
O-Transfer-facilitated cyclizations of propargylamides with TMSN3: Selective synthesis of tetrazoles and dihydroimidazoles
Hu, Yancheng,Yi, Ruxia,Yu, Xinzhang,Xin, Xiaoyi,Wang, Chunxiang,Wan, Boshun
supporting information, p. 15398 - 15401 (2015/10/20)
An unprecedented formal [3+2] annulation of propargylamides with TMSN3 to deliver functionalized tetrazoles is developed. Oxygen-atom transfer (OAT) from the amide group to the CC bond was realized via a NIS-triggered-cyclization/ring-opening cascade pathway. The OAT process enables the amide to serve as a two-atom unit in the reactions. Notably, in situ umpolung of azide occurred when terminal propargylamides were employed in this reaction, providing an array of diiodomethylated dihydroimidazoles.
Partial oxygen migration in the photochemical wolff rearrangement - α-Oxocarben-Oxiren-isomerization or intermolecular mechanism?
Haiss, Peter,Zeller, Klaus-Peter
, p. 595 - 605 (2007/10/03)
Crossover experiments between isotopomeric species of 2-diazo-1-oxo-1-phenylethane (18O, 13C, D) establish beyond doubt that the oxygen migration accompanying the photochemical Wolff rearrangement is not the result of intermolecular
Stereodefined synthesis of O3′-labeled uracil nucleosides. 3′-[17O]-2′-azido-2′-deoxyuridine 5′-diphosphate as a probe for the mechanism of inactivation of ribonucleotide reductases
Wnuk, Stanislaw F.,Chowdhury, Saiful M.,Garcia Jr., Pedro I.,Robins, Morris J.
, p. 1816 - 1819 (2007/10/03)
Thermolysis of a 2′-[16O]-O-benzoyl-[17O]-5′-O-(tert- butyldimethylsilyl)-O2,3′-cyclouridine derivative gave the more stable 3′-[17O]-O-benzoyl-[16O]-5′-O-(tert- butyldimethylsilyl)-O2,2′-cyclouridine isomer, which was converted into 3′-[17O]-2′-azido-2′-deoxyuridine by deprotection and nucleophilic ring opening at C2′ with lithium azide. The 5′-diphosphate was prepared by nucleophilic displacement of the 5′-O-tosyl group with tris(tetrabutylammonium) hydrogen pyrophosphate. Model reactions gave 16O and 18O isotopomers, and base-promoted hydrolysis of an O2,2′-cyclonucleoside gave stereodefined access to 3′-[18O]-1-(β-D-arabinofuranosyl)uracil. Inactivation of ribonucleoside diphosphate reductase with 2′-azido-2′-deoxynucleotides results in appearance of EPR signals for a nitrogen-centered radical derived from azide, and 3′-[17O]-2′-azido-2′-deoxyuridine 5′-diphosphate provides an isotopomer to perturb EPR spectra in a predictable manner.
