- Alkyl Nitrites: Novel Reagents for One-Pot Synthesis of 3,5-Disubstituted Isoxazoles from Aldoximes and Alkynes
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An efficient, one-pot approach has been described for the synthesis of 3,5-disubstituted isoxazoles from substituted aldoximes (mixture of E and Z) and alkynes, using alkyl nitrites under conventional heating conditions. The key nitrile oxide intermediates that are required for the synthesis of isoxazoles are formed by treatment of substituted aldoxime with either tert-butyl nitrite or isoamyl nitrite. The generated nitrile oxides underwent in situ [3+2] dipolar cycloaddition to the substituted alkynes to give 3,5-disubstituted isoxazoles regioselectively in high to excellent yields. The developed synthetic methodology was applied for the synthesis of a previously reported potent hDGAT1 inhibitor.
- Kadam, Kishorkumar S.,Gandhi, Thirumanavelan,Gupte, Amol,Gangopadhyay,Sharma, Rajiv
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p. 3996 - 4008
(2016/11/11)
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- Precipitons - Functional protecting groups to facilitate product separation: Applications in isoxazoline synthesis
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Imagine - After a homogeneous reaction is complete, the chemist adds a catalyst or exposes the reaction mixture to soft UV light and pure product precipitates from the reaction mixture. This can be achieved with "precipitons" - Protecting groups that have controllable solubility states. The first advances towards that goal are described (see scheme).
- Bosanac, Todd,Yang, Jaemoon,Wilcox, Craig S.
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p. 1875 - 1879
(2007/10/03)
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- Regioselective synthesis of C-nucleosides by 1,3-dipolar cycloaddition of arylnitrile oxides to 5,6-dideoxy-1,2-O-isopropylidene-α-D-xylo-hex-5-enofuranose
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The synthesis of 3-aryl-5-(1,2-O-isopropylidene-α-D-xylo-tetrofuranos-4-yl)-2-isoxazoline (3) from arylnitrile oxides and 5,6-dideoxy-1,2-O-isopropylidene-α-D-xylo-hex-5-enofuranose (1) is described.The 1,3-dipolar cycloaddition reactions give mainly anti-adducts (>=95percent ?-facial stereoselectivity).
- Al-Timari, Usama A. R.,Fisera, Lubor
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p. 121 - 127
(2007/10/02)
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- Organic Curing Agents for Polysulfide Sealants. III A Mechanistic Interpretation of the Thermal Degradation of Nitrile Oxide-Cured Polysulfide Sealants
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Sealants obtained by cure of polysulfide liquid polymers with aryl bis(nitrile oxides) possess the thiohydroximic acid ester structural feature.Unexpectedly these materials were found to exhibit poor thermal stability: when heated at 60 deg they soften wi
- Ennis, Brian C.,Hanhela, Peter J.,Paul, Brenton D.
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p. 109 - 124
(2007/10/02)
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- REACTIONS OF NITRILE OXIDES WITH NITROGEN OXIDES. 2. REACTIONS WITH NITROGEN MONOXIDE AND NITROGEN SESQUIOXIDE
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We have studied the reactions of aromatic nitrile oxides with nitrogen monoxide and nitrogen sesquioxide.It was shown that the nitrogen monoxide removes an oxygen atom from the nitrile oxide with formation of the corresponding nitrile and nitrogen dioxide.The reaction products with nitrogen sesquioxide are formed as a result of reactions of the nitrile oxide with nitrogen monoxide and nitrogen tetroxide.
- Rakitin, O. A.,Ogurtsov, V. A.,Godovikova, T. I.,Khmel'nitskii, L. I.
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p. 1472 - 1474
(2007/10/02)
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- SYNTHESES BASED ON NITRILE OXIDES. 1. REACTION OF AROMATIC NITRILE OXIDES WITH N-CYANAMIDES
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The reaction of trialkylaminocyanimides with aromatic nitrile oxides leads to trialkylamino-(3-aryl-1,2,4-oxadiazol-5-yl)imides, while the corresponding reactions with sulfylcyanimines and phosphincyanimides do not take place.Using x-ray structural analysis the principal structural features of the 1,2,4-oxadiazole products have been elucidated.
- Ogurtsov, V. A.,Rakitin, O. A.,Obruchnikova, N. V.,Chertanova, L. F.,Gazikasheva, A. A.,Khmel'nitskii, L. T.
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p. 1896 - 1900
(2007/10/02)
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- Dialkyl (3-Aryl-1,2,4-oxadiazol-5-yl)phosphonates: Synthesis and Thermal Behavior - Evidence for Monomeric Alkyl Metaphosphate
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Dialkyl (3-aryl-1,2,4-oxadiazol-5-yl)phosphonates 6a-h have been obtained by 1,3-dipolar cycloaddition of arenenitrile oxides 5a-f to dialkyl phosphorocyanidates (4a and 4b) in yields ranging between 30percent and 58percent.A standardized method for obtaining cyanidates 4a and 4b has been established.The diethyl thiophosphorocyanidate (4c) is less reactive than 4a and 4b, only the 3-(4'-nitrophenyl) derivative 6i being obtainable.While the IR and NMR spectra of 6a-6i were unexceptional, their UV spectra showed evidence of conjugative interaction in high degrees between the phosphonate and heterocyclic moieties as well as a varying conjugative interaction between the heterocyclic and aryl moieties.The oxadiazoles 6a-h are thermally labile and yield trialkyl phosphates 7 as the only identifiable products.A mechanism based on the intermediacy of monomeric alkyl metaphosphate 11 in the formation of trialkyl phosphate was postulated, and supportive evidence in the form of trapping the metaphosphate with acetophenone has been obtained.
- Das, Sushanta K.,Balasubrahmanyam, S. N.
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p. 4232 - 4236
(2007/10/02)
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- REACTION OF N-OXIDES OF AROMATIC NITRILES WITH α,β-UNSATURATED AZO COMPOUNDS
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The N-oxides of aromatic nitriles add at the C=C double bond of azoalkenes.The reaction is a method for the production of new derivatives of isoxazoline, i.e., 3-aryl-5-alkylazo-Δ2-isoxazolines.
- Vasil'eva, L. P.,Akimova, G. S.,Chistokletov, V. N.,Zelenin, K. N.
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p. 1621 - 1624
(2007/10/02)
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