- HNO made-easy from photochemical cycloreversion of novel 3,5-heterocyclic disubstituted 1,2,4-oxadiazole-4-oxides
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A variety of symmetric and asymmetric 3,5-heterocyclic disubstituted 1,2,4-oxadiazole-4-oxides have been prepared through cycloaddition of aromatic and heteroaromatic nitrile oxides to heteroaromatic amidoximes. A library of novel, fully characterized, 1,
- Memeo, Misal Giuseppe,Dondi, Daniele,Mannucci, Barbara,Corana, Federica,Quadrelli, Paolo
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p. 7387 - 7394
(2013/08/23)
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- Photogeneration and reactivity of acyl nitroso compounds
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Acyl nitroso compounds have been generated by photolysis of several different classes of precursors including 9,10-dimethylanthracene adducts, nitrodiazo compounds, and 1,2,4-oxadiazole-4-oxides. Consideration of the nitronate-like resonance structure of nitrodiazo compounds led to an examination of the photochemistry of nitronates with -leaving groups. Photolysis of such nitronates has been shown to generate an acyl nitroso species along with a carbene intermediate. Nanosecond time-resolved infrared (TRIR) spectroscopy has been used to detect photogenerated acyl nitroso compounds directly and to examine their reaction kinetics with amines and thiols. The mechanism of acyl nitroso aminolysis by primary amines involves general base catalysis, while the mechanism of aminolysis by secondary amines is strictly bimolecular. Thiols do not seem to be reactive with acyl nitroso compounds on the microsecond time scale, but thiolates are quite reactive. The reaction between benzoyl nitroside and an organic-soluble thiolate, tetrabutylammonium dodecanethiolate, proceeds via a proposed tetrahedral intermediate, which is observable by TRIR spectroscopy.
- Evans, Anthony S.,Cohen, Andrew D.,Gurard-Levin, Zachary A.,Kebede, Naod,Celius, Tevye C.,Miceli, Alexander P.,Toscano, John P.
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p. 130 - 138
(2011/04/23)
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- Oxidation of oximes to nitrile oxides with hypervalent iodine reagents
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Iodobenzene diacetate in MeOH containing a catalytic amount of TFA efficiently oxidizes aldoximes to nitrile oxides. The latter may be trapped in situ with olefins in a bimolecular or an intramolecular mode. The new method enables the execution of tandem oxidative dearomatization of phenols/intramolecular nitrile oxide cycloaddition sequences leading to useful synthetic intermediates.
- Mendelsohn, Brian A.,Lee, Shelley,Kim, Simon,Teyssier, Florian,Aulakh, Virender S.,Ciufolini, Marco A.
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supporting information; experimental part
p. 1539 - 1542
(2009/08/07)
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- Direct observation of an Acyl nitroso species in solution by time-resolved IR spectrocopy
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Benzoyl nitroside (5) was generated in solution by laser photolysis of 3,5-diphenyl-1,2,4-oxadiazole-4-oxide (4) and studied by time-resolved infrared spectroscopy. The second-order rate constantsfor reaction of 5 with diethylamine and 1,3-cyclohexadiene were determined to be (1.3 ± 0.5) × 105 M-1 s-1 and (6.0 ± 0.5) × 103 M-1 s-1, respectively. The formation of nitroxyl (HNO), a product of the reaction of 5 with diethylamine, was also observed. Copyright
- Cohen, Andrew D.,Zeng, Bu-Bing,King, S. Bruce,Toscano, John P.
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p. 1444 - 1445
(2007/10/03)
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- Unprecedented rearrangement reaction of nitrile oxides and a sterically congested 4-ylidene-5-isoxazolone
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The reaction between nitrile oxides and 4-diphenylmethylene-3-phenylisoxazol-5-one (5) proceeds in an unprecedented fashion to yield 4-diphenylmethylene-2,3,3-trisubstituted derivatives (10). Their structure was determined by an X-Ray diffraction study.
- Foti, Francesco,Grassi, Giovanni,Risitano, Francesco,Bruno, Giuseppe,Nicolo, Francesco
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p. 763 - 768
(2007/10/03)
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- Cycloadditions of nitrile oxides to amidoximes. A general synthesis of 3,5-disubstituted 1,2,4-oxadiazole-4-oxides
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The cycloaddition of nitrile oxides to amidoximes is a general method for the synthesis of 3,5-disubstituted 1,2,4-oxadiazole-4-oxides with the same or different substituents. The yields are only moderate since an equivalent amount of the nitrile oxide is consumed by reaction with the amine released in the fragmentation of the primary cycloadducts and reforms the amidoxime. With excess nitrile oxides the 1,2,4-oxadiazole-4-oxides undergo a disproportionation reaction to yield nitroso carbonyl intermediates and 1,2,4-oxadiazoles.
- Quadrelli, Paolo,Invernizzi, Anna Gamba,Falzoni, Mario,Caramella, Pierluigi
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p. 1787 - 1796
(2007/10/03)
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- SELECTIVITY IN CYCLOADDITIONS-IX CYCLOADDITIONS OF NITRILE OXIDES TO INDOLES. REACTIVITY AND REGIOCHEMISTRY
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Cycloadditions of benzonitrile oxide and mesitonitrile oxide to N-methylindole and indole yield the acid sensitive cycloadducts 1 a-d with high regioselectivity.With N-carbethoxyindole the stable cycloadducts 1 e,f and minor amounts of the regioisomeric 2 e,f are isolated.The electron withdrawing substituent reduces both the regioselectivity and the reactivity of the cycloadditions.Frontier orbital considerations, based on MINDO/3 calculations, allow elucidation of the observed changes in reactivity and regiochemistry.
- Caramella, P,Corsico, A. Coda,Corsaro, A,Del Monte, D.,Albini, F. Marinone
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p. 173 - 182
(2007/10/02)
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