In situ generated stabilized phosphorus ylides mediated a mild and efficient method for the preparation of some new sterically congested electron-poor N-vinylated heterocycles |
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Authors: | Mehdi Bahrami Younes Hanifehpour Nadia Fattahi Saeid Taghavi Fardood Pegah Azimzadeh Asiabi |
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Affiliation: | 1. Department of Chemistry, University of Zanjan, Zanjan, Iran;2. School of Mechanical Engineering, Yeungnam University, Gyeongsan, Republic of Korea |
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Abstract: | Protonation of the highly reactive 1:1 intermediate produced in the reaction between triphenylphosphine and an acetylenic ester by a N-H acid (4-phenylphthalazin-1(2 H)-one, 5,5-diphenylimidazolidine-2,4-dione) leads to the formation of a vinyltriphenylphosphonium salt. The cation of the salt undergoes an addition reaction with the counter anion in CH2Cl2 at room temperature to yield the corresponding stabilized phosphorus ylide. Elimination of triphenylphosphine from the stabilized phosphorus ylides leads to the formation of corresponding electron-poor N-vinylated heterocycles in moderate to high yields (67–95%). The reaction is completely regio- and stereoselective. |
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Keywords: | Electron-poor N-vinylated heterocycle acetylenic ester phosphorus ylide triphenylphosphine vinyltriphenylphosphonium salt stereoselective |
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