- Unexpected ring opening of pyrazolines with activated alkynes: synthesis of 1H-pyrazole-4,5-dicarboxylates and chromenopyrazolecarboxylates
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1H-Pyrazole-4,5-dicarboxylates and chromenopyrazole carboxylates were prepared by reacting pyrazolines with activated alkynes under neat conditions without a catalyst. The products were formed via unexpected ring opening of pyrazolines with the elimination of styrene/ethylene. These types of transformations are unknown and the products formed were confirmed using their spectral/analytical data. In addition, the structures of compounds 5e and 5n were confirmed by single-crystal X-ray analysis. Control experiments were conducted to support the proposed reaction mechanism.
- Bhimapaka, China Raju,Kolla, Sai Teja,Rayala, Nageswara Rao,Sridhar, Balasubramanian
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supporting information
p. 334 - 338
(2022/01/20)
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- Eclectic 1-Aryl-1,2-diazabuta-1,3-dienes: Valuable tools for the preparation of pyrrol-2-ones, 1-arylpyrazoles, 2-(3-oxopyrazol-4-yl)malonates and 4-(2-oxopyrrol-3-yl)pyrazol-3-ones
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1-Aryl-1,2-diazabuta-1,3-dienes react with dimethyl malonate to give hydrazonic intermediates that in turn are converted into pyrrol-2-ones, 1-arylpyrazoles and 2-(3-oxopyrazol-4-yl)malonates. The latter compounds represent an useful entry to 4-(2-oxopyrrol-3-yl)pyrazol-3-ones, by means of the addition of another molecule of 1,2-diazabuta-1,3-diene and subsequent cyclization of the adducts.
- Attanasi, Orazio A.,De Crescentini, Lucia,Favi, Gianfranco,Filippone, Paolino,Mantellini, Fabio,Santeusanio, Stefania
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p. 1546 - 1552
(2007/10/03)
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- 1,3-Dipolar Cycloadditions, 88. C-Methyl-N-phenylnitrilimine and the Regiochemistry of its Cycloadditions
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The title compound, a representative of the little known C-alkylnitrilimines, is accessible by three routes: NaNO2 elimination from sodium (α-nitroethylidene)phenylhydrazine in boiling acetonitrile, photolysis of 5-methyl-2-phenyltetrazole, and the thermo
- Fliege, Werner,Huisgen, Rolf,Clovis, James S.,Knupfer, Hans
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p. 3039 - 3061
(2007/10/02)
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