- The reaction of amidoximes with carboxylic acids or their esters under high-pressure conditions
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3,5-Disubstituted 1,2,4-oxadiazoles were synthesized by the reaction of amidoximes with carboxylic acids or their esters under high-pressure conditions (10 kbar). The reaction proceeds without the use of other reagents or catalysts. Both aliphatic and aro
- Baikov,Stashina,Chernoburova,Krylov,Zavarzin,Kofanov
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- SYNTHESIS AND SPECTROSCOPIC STUDIES OF 5-METHYL-3-PHENYL- AND 5-METHYL-3-(o-, m-, AND p-TOLYL)-1,2,4-OXADIAZOLES.
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Preparation of four 1,2,4-oxadiazoles, 2a-d, from O-acetyl derivatives of benzamidoximes, 1a-d, are reported. Two of them, viz. , 2b,c, were not encountered in the literature. Spectroscopic studies (IR, UV, and **1H NMR) were carried out to learn more abo
- Srivastava,Mendes e Silva
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- Reaction of amidoximes with acetonitrile at high pressure
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Reaction of amidoximes with acetonitrile giving 1,2,4-oxadiazoles occurs at 80-100 °C under a pressure of 10 Kbar without catalysts.
- Baykov, Sergey V.,Zharov, Aleksey A.,Stashina, Galina A.,Zavarzin, Igor V.,Kofanov, Evgeniy R.
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- 2-Iodosylbenzoic acid activated by trifluoromethanesulfonic anhydride: Efficient oxidant and electrophilic reagent for preparation of iodonium salts
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2-Iodosylbenzoic acid in the presence of trifluoromethanesulfonic anhydride is an efficient oxidant and electrophilic reagent useful for preparation of the corresponding alkenyl and aryliodonium salts. Compared to the previously reported methods of electr
- Huss, Christopher D.,Kitamura, Tsugio,Saito, Akio,Yoshimura, Akira,Zhdankin, Viktor V.
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supporting information
p. 16434 - 16437
(2021/10/01)
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- Convenient one-pot synthesis of 1,2,4-oxadiazoles and 2,4,6-triarylpyridines using graphene oxide (GO) as a metal-free catalyst: Importance of dual catalytic activity
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A convenient and efficient process for the synthesis of 3,5-disubstituted 1,2,4-oxadiazoles and 2,4,6-triarylpyridines has been described using an inexpensive, environmentally benign, metal-free heterogeneous carbocatalyst, graphene oxide (GO). GO plays a dual role of an oxidizing agent and solid acid catalyst for synthesizing 1,2,4-oxadiazoles and triarylpyridines. This dual catalytic activity of GO is due to the presence of oxygenated functional groups which are distributed on the nanosheets of graphene oxide. A broad scope of substrate applicability and good sustainability is offered in this developed protocol. The results of a few control experiments reveal a plausible mechanism and the role of GO as a catalyst was confirmed by FTIR, XRD, SEM, and HR-TEM analysis.
- Basak, Puja,Dey, Sourav,Ghosh, Pranab
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p. 32106 - 32118
(2021/12/02)
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- Imidazole hydrochloride promoted synthesis of 3,5-disubstituted-1,2,4-oxadiazoles
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Imidazole hydrochloride as an additive promotes the reaction of amidoximes and DMA derivatives to generated 3,5-disubstituted-1,2,4-oxadiazoles in low to excellent yields without the use of coupling reagents, oxidants, strong acids or bases and other additives.
- Wang, Xuetong,Wang, Yin,Liu, Xiaoling,He, Tingshu,Li, Lingli,Wu, Huili,Zhou, Shangjun,Li, Dan,Liao, Siwei,Xu, Ping,Huang, Xing,Yuan, Jianyong
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supporting information
(2021/10/14)
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- Efficient insecticidal aerosol and preparation method thereof
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The invention provides an efficient insecticidal aerosol, which comprises the following components in percentage by weight: 0.1-0.5wt% of a component A, i.e. a 1, 2, 4-diazole derivative shown as a formula I, 1-1.5wt% of a component B, i.e. a marigold ext
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Paragraph 0035; 0046-0048; 0053-0054; 0081; 0092-0094; 0099
(2020/10/30)
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- Potassium Poly(Heptazine Imide): Transition Metal-Free Solid-State Triplet Sensitizer in Cascade Energy Transfer and [3+2]-cycloadditions
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Polymeric carbon nitride materials have been used in numerous light-to-energy conversion applications ranging from photocatalysis to optoelectronics. For a new application and modelling, we first refined the crystal structure of potassium poly(heptazine imide) (K-PHI)—a benchmark carbon nitride material in photocatalysis—by means of X-ray powder diffraction and transmission electron microscopy. Using the crystal structure of K-PHI, periodic DFT calculations were performed to calculate the density-of-states (DOS) and localize intra band states (IBS). IBS were found to be responsible for the enhanced K-PHI absorption in the near IR region, to serve as electron traps, and to be useful in energy transfer reactions. Once excited with visible light, carbon nitrides, in addition to the direct recombination, can also undergo singlet–triplet intersystem crossing. We utilized the K-PHI centered triplet excited states to trigger a cascade of energy transfer reactions and, in turn, to sensitize, for example, singlet oxygen (1O2) as a starting point to synthesis up to 25 different N-rich heterocycles.
- Antonietti, Markus,Guldi, Dirk M.,Hussain, Tanveer,Karton, Amir,Markushyna, Yevheniia,Mazzanti, Stefano,Oschatz, Martin,Sánchez Vadillo, José Manuel,Savateev, Aleksandr,Strauss, Volker,Tarakina, Nadezda V.,Tyutyunnik, Alexander P.,Walczak, Ralf,ten Brummelhuis, Katharina
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supporting information
p. 15061 - 15068
(2020/06/17)
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- Efficient Synthesis of Functionalized Indene Derivatives via Rh(III)-Catalyzed Cascade Reaction between Oxadiazoles and Allylic Alcohols
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A highly efficient rhodium(III)-catalyzed synthesis of novel functionalized indene derivatives has been achieved via C?H activation/intramolecular aldol condensation. This cascade reaction is an atom economical protocol which could be further applied to build more complex compounds. (Figure presented.).
- Zhang, Jing,Sun, Jun-Shu,Xia, Ying-Qi,Dong, Lin
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supporting information
p. 2037 - 2041
(2019/03/28)
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- Rhodium-catalyzed synthesis of 1-(acylamino)isoquinolines through direct annulative coupling of 3-aryl-1,2,4-oxadiazoles with alkynes
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A Rh(III)-catalyzed direct annulative coupling of 3-aryl-1,2,4-oxadiazoles with alkynes through coordination-assisted CH activation is developed, providing a facile route to 1-(acylamino)isoquinolines. The oxadiazole ring acts as a directing group as well as an internal oxidant.
- Nishii, Yuji,Bachon, Anne-Katrin,Moon, Sanghun,Bolm, Carsten,Miura, Masahiro
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supporting information
p. 1347 - 1349
(2017/08/14)
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- Cobalt(III)-Catalyzed Oxadiazole-Directed C-H Activation for the Synthesis of 1-Aminoisoquinolines
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Aromatic heterocycles have been identified as effective directing groups (DGs) in C-H functionalization but can be retained as undesired bulky substituents in the final products. Herein, we report a Co(III)-catalyzed 1-aminoisoquinoline synthesis strategy based on oxadiazole-directed aromatic C-H coupling with alkynes and a subsequent redox-neutral C-N cyclization reaction. This labile N-O bond-based protocol has allowed the toleration of a broad range of functional groups.
- Yang, Fan,Yu, Jiaojiao,Liu, Yun,Zhu, Jin
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supporting information
p. 2885 - 2888
(2017/06/07)
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- A convenient and mild method for 1,2,4-oxadiazole preparation: Cyclodehydration of O-acylamidoximes in the superbase system MOH/DMSO
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Herein, we reported a general, convenient, and efficient synthesis of 3,5-disubstituted-1,2,4-oxadiazoles via cyclodehydration of O-acylamidoximes in the superbase system MOH/DMSO (M = Li, Na, K). Excellent isolated yields (up to 98%) were attained within
- Baykov, Sergey,Sharonova, Tatyana,Osipyan, Angelina,Rozhkov, Sergey,Shetnev, Anton,Smirnov, Alexey
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supporting information
p. 2898 - 2900
(2016/06/14)
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- Preparation, structure, and versatile reactivity of pseudocyclic benziodoxole triflate, new hypervalent iodine reagent
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A new pseudocyclic triflate derivative of benziodoxole (IBA-OTf) was prepared and characterized by X-ray analysis. This highly electrophilic reagent readily reacts with various organic substrates to give the corresponding products in good yields. Furthermore, IBA-OTf can be used as a catalyst with m-chloroperoxybenzoic acid as the terminal oxidant. This journal is
- Yoshimura, Akira,Nguyen, Khiem C.,Klasen, Scott C.,Saito, Akio,Nemykin, Victor N.,Zhdankin, Viktor V.
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supporting information
p. 7835 - 7838
(2015/05/13)
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- Construction of 3,5-substituted 1,2,4-oxadiazole rings triggered by tetrabutylammonium hydroxide: A highly efficient and fluoride-free ring closure reaction of O-acylamidoximes
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Tetrabutylammonium hydroxide (TBAH) is an efficient and mild alternative to tetrabutylammonium fluoride (TBAF) for base catalyzed cyclizations of 1,2,4-oxadiazoles from O-acylamidoximes. For most 3,5-substituted 1,2,4-oxadiazoles the reactions were dramatically accelerated by addition of 0.1 equiv of TBAH at room temperature. This method was also more generally applicable allowing for a wider range of substrates. Additionally, due to the absence of fluoride, TBAH will not result in corrosion of reactor vessels and therefore is better suited for large-scale synthesis.
- Otaka, Hiromichi,Ikeda, Junya,Tanaka, Daisuke,Tobe, Masanori
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p. 979 - 981
(2014/02/14)
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- Construction of 3,5-substituted 1,2,4-oxadiazole rings triggered by tetrabutylammonium hydroxide: A highly efficient and fluoride-free ring closure reaction of O-acylamidoximes
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Tetrabutylammonium hydroxide (TBAH) is an efficient and mild alternative to tetrabutylammonium fluoride (TBAF) for base catalyzed cyclizations of 1,2,4-oxadiazoles from O-acylamidoximes. For most 3,5-substituted 1,2,4-oxadiazoles the reactions were dramatically accelerated by addition of 0.1 equiv of TBAH at room temperature. This method was also more generally applicable allowing for a wider range of substrates. Additionally, due to the absence of fluoride, TBAH will not result in corrosion of reactor vessels and therefore is better suited for large-scale synthesis.
- Otaka, Hiromichi,Ikeda, Junya,Tanaka, Daisuke,Tobe, Masanori
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p. 979 - 981
(2015/02/02)
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- Efficient and convenient protocol for the synthesis of 3,5-disubstituted 1,2,4-oxadiazoles using HClO4-SiO2 as a heterogeneous recyclable catalyst
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Silica-supported perchloric acid (HClO4SiO2) was found to be a new, highly efficient, inexpensive, and reusable catalyst for a rapid and efficient synthesis of various 1,2,4-oxadiazoles with good to excellent yields under solvent-free conditions. The present methodology has been effectively utilized for the synthesis of oxolamine, an anti-inflammatory drug.
- Tadikonda, Ramu,Nakka, Mangarao,Gajula, Mahaboob Basha,Rayavarapu, Srinuvasarao,Gollamudi, Padma Rao,Vidavalur, Siddaiah
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supporting information
p. 1978 - 1986
(2014/07/07)
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- Mild and efficient one-pot synthesis of 3,5-disubstituted 1,2,4-oxadiazoles from nitriles mediated by K 3PO 4
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Potassium phosphate, K3PO4, has been proved to be a cheap, strong, and efficient reagent for the one-pot synthesis of 3,5-disubstituted-1,2,4-oxadiazoles from nitriles and acid chlorides under mild conditions. [Supplementary material
- Movassagh, Barahman,Talebsereshki, Farzaneh
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supporting information
p. 188 - 194
(2013/12/04)
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- Some regularities of the synthesis of ethyl 3-aryl-1,2,4-oxadiazole-5-carboxylates
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Features of amidoximes reactions with ethyl chlorooxalate in a wide range of solvents at the use of a number of bases were investigated. An efficient preparation method for ethyl 3-aryl-1,2,4-oxadiazole-5-carboxylates in acetonitrile in the presence of triethylamine was developed.
- Voronova,Baikov,Krasovskaya,Kolobov,Kofanov
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p. 1683 - 1686
(2015/02/02)
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- Br?nsted acid-catalyzed simple and efficient synthesis of 1,2,4-triazoles and 1,2,4-oxadiazoles using 2,2,2-trichloroethyl imidates in PEG
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A facile and highly efficient synthesis of 3,4,5-trisubstituted 1,2,4-triazoles and 3,5-disubstituted 1,2,4-oxadiazoles from 2,2,2-trichloroethyl imidates using PEG as a solvent and employing PTSA as the catalyst under mild conditions is described.
- Mangarao, Nakka,Mahaboob Basha, Gajula,Ramu, Tadikonda,Srinuvasarao, Rayavarapu,Prasanthi, Sarakula,Siddaiah, Vidavalur
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supporting information
p. 177 - 179
(2014/01/06)
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- A simple and straightforward protocol to 3,5-disubstituted 1,2,4-oxadiazoles from carboxylic acids
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A convenient one-pot synthesis of 1,2,4-oxadiazoles is described. The condensation of carboxylic acids and amidoximes in the presence of 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) and N-methylmorpholine (NM1 B) has been employed to synthesize a variety of 3,5-disubstituted 1,2,4-oxadiazoles in good to excellent yields. The methodology has been applied for the synthesis of a metabotropic glutamate subtype 5 (mGlu5) receptor antagonist.
- Ramu, Tadikonda,Prasanthi, Sarakula,Mangarao, Nakka,Basha, Gajula Mahaboob,Srinuvasarao, Rayavarapu,Siddaiah, Vidavalur
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supporting information
p. 722 - 724
(2013/07/26)
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- PTSA-ZnCl2: An efficient catalyst for the synthesis of 1,2,4-oxadiazoles from amidoximes and organic nitriles
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(Chemical Equation Presented) PTSA-ZnCl2 has been proved to be an efficient and mild catalyst for the synthesis of 3,5-disubstituted-1,2,4- oxadiazoles from amidoximes and organic nitriles.
- Augustine, John Kallikat,Akabote, Vani,Hegde, Shrivatsa Ganapati,Alagarsamy, Padma
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scheme or table
p. 5640 - 5643
(2009/12/08)
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- A novel, one-pot, three-component synthesis of 1,2,4-oxadiazoles under microwave irradiation and solvent-free conditions
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A novel synthesis of 3,5-disubstituted 1,2,4-oxadiazoles is described from a one-pot, three-component reaction between nitriles, hydroxylamine, and Meldrum's acids under microwave irradiation and solvent-free conditions in good to excellent yields. Georg
- Adib, Mehdi,Mahdavi, Mohammad,Mahmoodi, Niusha,Pirelahi, Hooshang,Bijanzadeh, Hamid Reza
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p. 1765 - 1767
(2008/02/04)
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- Antikinetoplastid activity of 3-aryl-5-thiocyanatomethyl-1,2,4-oxadiazoles
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A series of 5-thiocyanatomethyl- and 5-alkyl-3-aryl-1,2,4-oxadiazoles were synthesized and evaluated for their activity against kinetoplastid parasites. Formation of the oxadiazole ring was accomplished through the reaction of benzamidoximes with acyl chlorides, while the thiocyanate group was inserted by reacting the appropriate 5-halomethyl oxadiazole with ammonium thiocyanate. The thiocyanate-containing compounds possessed low micromolar activity against Leishmania donovani and Trypanosoma brucei, while the 5-alkyl oxadiazoles were less active against these parasites. 3-(4-Chlorophenyl)-5-(thiocyanatomethyl)-1, 2,4-oxadiazole (compound 4b) displayed modest selectivity for L. donovani axenic amastigote-like parasites over J774 macrophages, PC3 prostate cancer cells, and Vero cells (6.4-fold, 3.8-fold, and 9.1-fold, respectively), while 3-(3,4-dichlorophenyl)-5-(thiocyanatomethyl)-1,2,4-oxadiazole (compound 4h) showed 30-fold selectivity against Vero cells but was not selective against PC3 cells. In a murine model of visceral leishmaniasis, compound 4b decreased liver parasitemia caused by L. donovani by 48% when given in five daily i.v. doses at 5mg/kg and by 61% when administered orally for 5days at 50mg/kg. These results indicate that aromatic thiocyanates hold promise for the treatment of leishmanial infections if the selectivity of these compounds can be improved.
- Cottrell, Denise M.,Capers, Jeffrey,Salem, Manar M.,DeLuca-Fradley, Kate,Croft, Simon L.,Werbovetz, Karl A.
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p. 2815 - 2824
(2007/10/03)
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- Preparation of 3,5-disubstituted 1,2,4-oxadiazoles by reactions of nitrilium salts with amide oximes
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The reaction of N-alkyl- and N-arylnitrilium salts 1a,d,g,j with the amide oximes 2a-c furnished the new iminium salts 3a-k (76-93%). On heating, compounds 3a-c cyclized to salts, which were transformed with base to the 3,5-disubstituted 1,2,4-oxadiazoles 4a-c in good yields (ca. 80%).
- Moustafa, Ahmed H.
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p. 837 - 840
(2007/10/03)
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- One-pot synthesis of 1,2,4-oxadiazoles mediated by microwave irradiation under solvent-free condition
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Microwave-assisted synthesis of 1,2,4-oxadiazoles of amidoximes under solvent free conditions was found to be an efficient method for one-pot synthesis of 1,2,4-oxadiazole derivatives from amidoximes and acyl chlorides. This method is an easy, rapid, and
- Kaboudin, Babak,Navaee, Kian
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p. 2287 - 2292
(2007/10/03)
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- Synthesis of 3,5-disubstituted-1,2,4-oxadiazoles using tetrabutylammonium fluoride as a mild and efficient catalyst
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Tetrabutylammonium fluoride (TBAF) was found to be a mild and efficient catalyst for the synthesis of 3,5-disubstituted-1,2,4-oxadiazoles. Using 0.1 - 1.0 equivalents of TBAF in THF for 1 - 24 h at room temperature, alkanoyl- and aroyloxyamidines were converted in high yield to the corresponding 3,5-disubstituted-1,2,4-oxadiazoles. A variety of R and R′ substituents were investigated.
- Gangloff, Anthony R.,Litvak, Joane,Shelton, Emma J.,Sperandio, David,Wang, Vivian R.,Rice, Kenneth D.
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p. 1441 - 1443
(2007/10/03)
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- Ceric ammonium nitrate oxidation of aldoximes in aliphatic nitriles as solvents: A new way for synthesis of 1,2,4-oxadiazoles
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Oxidation of aromatic aldoximes with one-electron oxidant ceric ammonium nitrate CAN in acetonitrile and propionitrile, has been investigated. Aromatic nitrile oxides, formed in situ, underwent 1,3-cycloaddition with aliphatic nitriles and 5-alkyl-3-aryl-1,2,4-oxadiazoles are produced in moderate to high yields. The mechanism of the reaction based on the transformations of intermediate aldazine di-N-oxides is discussed.
- Giurg,Mlochowski
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p. 1093 - 1101
(2007/10/03)
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- Reactions of Amidoximes with Orthoacetates
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The reaction of two amidoximes 4 with ethyl orthoacetate in the presence of an acid catalyst gave triazine N-oxides 7.A mechanism via a Beckmann rearrangement to a carbodiimide, followed by reaction with amidoxime and the ortho ester, is proposed.
- Kaugars, Girts,Watt, William
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p. 497 - 500
(2007/10/02)
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- Reactions of Oximes with Thianthrene Cation Radical in Nitrile Solvents. Cycloaddition To Form Oxadiazoles and Deoxygenation To Form Nitriles
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Reactions of eight oximes, RCH=NOH (1a, R= C6H5; 1b, R= 4-CH3C6H4; 1c, R= 4-NO2C6H4; 1d, R= 4-CH3OC6H4; 1e, R= 2-CH3OC6H4; 1f, R= 1-naphthyl; 1g, R= C5H11; 1h, R= C4H9), with thianthrene cation radical perchlorate (Th.+ClO4-) in acetonitrile under argon were studied.The major product from the oxime in all cases, but of 1d, was the nitrile, RCN.The anticipated product of oxidative cycloaddition, namely, a 3-R-5-methyl-1,2,4-oxadiazole (2), was obtained in substantial yield (2d, 66percent) only in the case of 1d.An isomeric 5-R-3-methyl-1,2,4-oxadiazole (3) was obtained from some reactions, that is, 3c alone from 1c, and a mixture of 2a and 3a from 1a.Neither 2 nor 3 was obtained in measurable amounts from reactions of 1g and 1h.The aldehyde (RCHO) was obtained in small yields from each reaction.Thianthrene (Th) and thianthrene 5-oxide (ThO) were also major products.Studies with -1b and -1d showed that the oxgen atom in 2 came entirely and in ThO primarily from the oxime.Studies of workup with H218O showed that the workup water was the source of the oxgen atom in RCHO and to a small extent in ThO.Explanations are given for the formation of 2 by a stepwise addition of RCH=NOH.+ (1.+) to solvent nitrile and of 3 by the reaction of solvent nitrile with an oxaziridine cation radical (7, obtained from 1.+).
- Chiou, Shishue,Hoque, A. K. M. M.,Shine, Henry J.
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p. 3227 - 3232
(2007/10/02)
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- THERMAL REACTIONS OF ARYLAMIDOXIMES
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The effect of heat on arylamidoximes, 1a-g, has been examined.When acetic acid was used as solvent, amidoximes, 1a-g, provided three products, viz., 3,5-bis-aryl-1,2,4-oxadiazoles, 2a-g, 3-aryl-5-methyl-1,2,4-oxadiazoles, 3a-g, and a small quantity of an
- Leite, Lucia F. C. da Costa,Srivastava, Rajendra M.,Cavalcanti, Alexandre P.
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p. 203 - 210
(2007/10/02)
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- A Simplified Procedure for Preparing 3,5-Disubstituted-1,2,4-Oxadiazoles by Reaction of Amidoximes with Acyl Chlorides in Pyridine Solution
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3-R-5-R'-1,2,4-Oxadiazoles are prepared in fair to good yield by short-time, one-pot reaction of an amidoxime, RC(NH2)NOH, with an acyl chloride, R'COCl, in pyridine solution.Precipitation of the oxadiazole occurs on diluting the pyridine reaction solutio
- Chiou, Shishue,Shine, Henry J.
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p. 125 - 128
(2007/10/02)
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- SYNTHESIS AND THERMOLYSIS OF SOME N-HYDROXIMOYL- AND N-HYDRAZONOYLAZOLES
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The reactions of nitrile oxides or nitrile imines with pyrazole, imidazole, 1,2,3- and 1,2,4-triazole or tetrazole derivatives yield the appropriate N-hydroximoyl- or N-hydrazonoylazoles.Thermolysis of 1-hydroximoyltetrazoles, depending on the nature of the substituents in the tetrazole ring, yields 1,2,4-oxadiazoles or 5-amino-1,2,4-oxadiazoles upon hydrazoic acid or nitrogen evolution.Under similar conditions, 1-hydrazonoyltetrazoles give 1,2,4-triazoles or 5-amino-1,2,4-triazoles while 2-hydrazonoyltetrazoles decompose to the dihydro-1,2,4,5-tetrazine derivatives.
- Plenkiewicz, Jan,Zdrojewski, Tadeusz
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p. 675 - 710
(2007/10/02)
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- Iminophosphorane-Mediated Synthesis of 3,5-Disubstituted 1,2,4-Oxadiazoles
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A number of 3,5-disubstituted-1,2,4-oxadiazoles have been prepared by intramolecular aza-Wittig condensation of iminophosphorane derivatives 3.
- Molina, P.,Alajarin, M.,Ferao, A.
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p. 843 - 845
(2007/10/02)
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- Direct Synthesis of 5-Methyl-3-aryl-1,2,4-oxadiazoles from Aryl Aldehydes, Nitroethane, and Ammonium Acetate
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The condensation of 2,5-dimethoxybenzaldehyde (1b) with nitroethane and ammonium acetate in glacial acetic acid has been found to give three diffrent products, depending on reactant ratio and reaction time.At an aldehyde:nitroethane:ammonium acetate ratio of 1:1.5:0.8 a normal Knoevenagel condensation occured, yielding 1-(2,5-dimethoxyphenyl)-2-nitropropene.At a reactant ratio of 1:3:2 (same reactant sequence), the primary product was 2,5-dimethoxybenzonitrile, and at a reactant ratio of 1:40:8, with extended reflux time, the major product was 3-(2,5-dimethoxyphenyl)-5-methyl-1,2,4-oxadiazole (8b).This last reaction served as a prototype for a new oxadiazole synthesis which was then extended to include six additional 5-methyl-3-aryl-1,2,4-oxadiazoles (8a,c-g; where aryl = Ph, 2,5-dimethoxyphenyl, 2,4-dichlorophenyl, m-chlorophenyl, p-tolyl, 3,5-dimethoxyphenyl, and p-carboxyphenyl), whose structures were assigned on the basis of 13C NMR characteristics of known reference compounds.Benzonitrile also reacted with excess nitroethane and ammonium acetate to yield 5-methyl-3-phenyl-1,2,4-oxadiazole (8a).The overall mechanism of oxadiazole formation is shown to be dependent on a preliminary reaction wherein the nitroalkane, in the presence of ammonium acetate and acetic acid, is first transformed into the corresponding alkanoic acid and hydroxylamine.Hydroxylamine then converts the aromatic aldehyde, via the intermediary nitrile, to the oxadiazoles following reactions of established precedent.
- Young, Thomas E.,Beidler, William Thomas
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p. 1182 - 1186
(2007/10/02)
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- Hydrogenolysis of the C-O Bond of the 1,2,4-Oxadiazine Ring. Adams Platinum Hydrogenation of 3-Aryl-5,6-dihydro-5-(substituted)-methylene-4H-1,2,4-oxadiazine Derivatives
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Adams platinum hydrogenation of Z-3-aryl-5,6-dihydro-5-(substituted)methylene-4H-1,2,4-oxadiazine (1a-f) proceeds very slowly through C-O bond fission to give N-(1-substitutedcarbonyl-2-propylidene)benzamide oxime derivative 2 as the main product.In the reaction of 5-(arylcarbamoyl)methylene analogues 1d-f, 5-(arylcarbamoyl)methyl-5,6-dihydro-3-phenyl-4H-1,2,4-oxadiazine (4) and N-aryl-3-hydroxybutanamide derivative 5 are also obtained as well as compound 2.
- Kawashima, Etsuko,Takada, Toyozo,Tabei, Katsumi
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p. 1409 - 1412
(2007/10/02)
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- Reaction of N-Aroyl-N-t-butylhydroxylamines with Thionyl Chloride. Synthesis of Substituted Benzohydroximoyl Chlorides
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The reaction of N-benzoyl-N-t-butylhydroxylamine with thionyl chloride in carbon tetrachloride gave O-chlorosulfinylbenzohydroximoyl chloride as the main product.On treating with ethanol, the compound gave benzohydroximoyl chloride in good yield.The reaction was applied to the synthesis of substituted benzohydroximoyl chlorides.
- Uchida, Yuzuru,Kozuka, Seizi
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p. 2011 - 2012
(2007/10/02)
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- Amidrazones. 8 . Synthesis of 1,2,4-Oxadiazoles by Thermolysis of N3-Acylamidrazone Ylides
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N3-Acylamidrazone ylides 3 were synthesized by the reaction of 2-(iminophenylmethyl)-1,1,1-trimethylhydrazinium hydroxide, inner salt (2a) or 2-(1-iminoethyl)-1,1,1-trimethylhydrazinium hydroxide, inner salt (2b) with acyl chlorides or acetic anhydride.Thermolysis of 3 gave 3,5-disubstituted oxadiazoles 4 and trimethylamine.
- Smith, Richard F.,Coffman, Karen J.,Geer, Susan M.
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- Formation and Thermal Reaction of O-(N-Acetylbenzimidoyl)benzamidoxime: Comparison with the Formation of 3,5-Disubstituted 1,2,4-Oxadiazoles from O-Acetylarylamidoximes and O-Aroylacetamidoximes
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Salts of O-(benzimidoyl)benzamidoxime have been obtained by the action of N-chloro- or N-bromo-succinimide, or the halogens, on benzamidoxime.Acetylation of the free base gave the title compound, which underwent a thermal cyclisation, with loss of acetamide, to give 3,5-diphenyl-1,2,4-oxadiazole.The mechanism of the reaction, in diphenyl ether, closely paralleled the thermal cyclisation of O-acetylarylamidoximes and O-aroylacetamidoximes, and is thought to involve a polar cyclisation step followed by rate-determining proton transfer. 13C N.m.r. spectra for 32 oxime, amidoxime, O-acetylamidoxime, 5-methyl-1,2,4-oxadiazol-3-yl, and 3-methyl-1,2,4-oxadiazol-5-yl groups on the phenyl ring are calculated.
- Ooi, Ngan Sim,Wilson, David A.
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p. 1792 - 1799
(2007/10/02)
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