Dipotassium Hydrogen Phosphate Powder-Catalyzed Stereoselective Synthesis of N-Vinyl Pyrazoles in Solvent-Free Conditions |
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| Authors: | Ali Ramazani Issa Amini Abdolhossain Massoudi |
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| Institution: | 1. Chemistry Department , Zanjan University , Zanjan , Iran;2. Chemistry Department , Peyam Noor University of Abhar , Abhar , Iran;3. Chemistry Department , Peyam Noor University of Mashhad , Mashhad , Iran;4. Chemistry Department , Peyam Noor University of Mashhad , Mashhad , Iran |
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| Abstract: | Protonation of the highly reactive 1:1 intermediates, which are produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates, by 3,5-dimethylpyrazol leads to vinyltriphenylphosphonium salts, which undergo a Michael addition reaction with a conjugate base to produce dialkyl 2-(3,5-dimethyl1H-pyrazol-1-yl)-3-(triphenylphosphoranylidene)butanedioates. Dipotassium hydrogen phosphate powder was found to catalyze the stereoselective conversion of dialkyl 2-(3,5-dimethyl-1H-pyrazol-1-yl)-3-(triphenylphosphoranylidene) butanedioates to dialkyl 2-(3,5-dimethyl-1H-pyrazol-1-yl)-2-butenedioates in solvent-free conditions under microwave (0.6 KW, 3 min) and thermal (90°C, 60 min) conditions. |
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| Keywords: | 3 5-dimethylpyrazol acetylenic esters dipotassium hydrogen phosphate Michael addition microwave irradiation vinyltriphenylphosphonium salt |
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