Sequential one-pot and three-component reactions of an N-heterocyclic carbene to form 4-(1,2,4-triazol-5-ylidene)pyrrolidine-2,5-diones: a tandem umpolung/annulation sequence via deoxy-Breslow intermediates |
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Authors: | Shin-ichi Matsuoka Yusuke TochigiKoji Takagi Masato Suzuki |
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Institution: | Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan |
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Abstract: | The tandem sequence of the umpolung of α,β-unsaturated esters by an N-heterocyclic carbene (NHC) followed by annulation is demonstrated. The deoxy-Breslow intermediates are selectively generated from the reaction of NHC with methyl methacrylate, dimethyl itaconate, or methyl crotonate. Subsequently, they undergo annulation with isocyanates to give 4-(1,2,4-triazol-5-ylidene)pyrrolidine-2,5-diones in good isolated yields. In addition, the stoichiometric three-component reaction of NHC, methyl methacrylate, and phenyl isocyanate proceeded, accompanied by the formation of the 1:2 adduct of NHC with phenyl isocyanate. |
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Keywords: | N-Heterocyclic carbene Sequential one-pot reaction Three-component reaction Umpolung Deoxy-Breslow intermediate |
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