- Tandem organocatalyzed knoevenagel condensation/1,3-dipolar cycloaddition towards highly functionalized fused 1,2,3-triazoles
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Facile synthesis of fused 1,2,3-triazoles by a proline-catalyzed reaction of an azido aldehyde and a nitroalkane is elaborated. The present tandem protocol proceeds via an organocatalytic Knoevenagel condensation of the azido aldehyde and nitroalkane followed by intramolecular azide-nitroalkene cycloaddition. The functionalized bicyclic triazole is obtained by elimination of HNO2 from the cycloadduct. Application of this strategy enabled us to synthesize a range of functionalised 5-7 membered ring fused triazoles. The reaction calls for mild conditions, affords high yields, and results in good regiospecificity while displaying excellent substrate scope.
- John, Jubi,Thomas, Joice,Parekh, Nikita,Dehaen, Wim
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supporting information
p. 4922 - 4930
(2015/08/03)
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- Reactivity of [60]Fullerene with primary nitro compounds: Addition or catalysed condensation to isoxazolo[60]fullerenes
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The catalysed condensation of [60]fullerene with ethyl nitroacetate (1b) or analogous activated nitro derivatives to afford isoxazolino[60]fullerenes has been achieved in both homogeneous and heterogeneous conditions. This direct synthetic approach is more convenient than previous methods. Model reactions with electron-poor dipolarophiles led to either condensation to isoxazolines or to conjugate addition products, depending on the nitro compound and catalyst. The former product was favoured by the use of CuII in the catalytic system. Conversely, [60]fullerene underwent catalytic condensation, even in the absence of copper(II) salts, only with activated nitro compounds and addition only with nitroalkanes in excess base. Note, the formal conjugated fullerene addition product was obtained in isomeric form, as previously reported. A possible explanation is presented for this contrasting behaviour.
- Biagiotti, Giacomo,Cicchi, Stefano,De Sarlo, Francesco,Machetti, Fabrizio
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p. 7906 - 7915
(2015/02/02)
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- Diethyl [Nitro(diazo)methyl]phosphonate: Synthesis and reactivity towards alkenes
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A novel and convenient synthesis of diethyl [nitro(di-azo)methyl] phosphonate and its reactions with various alkenes are described. The reactivity of diethyl [nitro(diazo)methyl]phosphonate is shown to be dependent on the structure of the alkene. A number of cyclopropyl-nitrophosphonates were obtained. Georg Thieme Verlag Stuttgart.
- Chemagin, Andrey V.,Yashin, Nikolai V.,Grishin, Yuri K.,Kuznetsova, Tamara S.,Zefirov, Nikolai S.
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experimental part
p. 259 - 266
(2010/03/24)
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- Approaches to the Synthesis of Retronecine from Some Pyrrolidine Precursors
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Procedures are described for the attempted conversion of the pyrrolidine (2) into a bicyclic system that would ultimately lead to retronecine (3). The only molecule to be isolated from these attempts was the epimeric ketone (6), and AM1 and MM2 calculations were used to probe this apparently favoured isomerization. Alternative procedures were then investigated that sought to convert the pyrrolidine (1) into precursors to retronecine, and notable successes were obtained with the addition of the amine (21) to both nitroethene and ethyl 2-diethylphosphonoacrylate. However, not only were these precursors resistant to further transformations into retronecine, but also the problem of epimerization again arose. Consequently, AM1 calculations were again employed, and an X-ray structure determination of ethyl (7R,8R)-7-benzyloxy-1-benzyloxymethyl-5,6,7,8-tetrahydro-3H-pyrrolizine-2-carboxylate (39) is reported. Attempts to convert (39) into a diastereoisomer of retronecine were unsuccessful.
- Clare, Brian W.,Ferro, Vito,Skelton, Brian W.,Stick, Robert V.,White, Allan H.
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p. 805 - 824
(2007/10/02)
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