Microwave-assisted cycloaddition of diisopropyl diazomethylphosphonate to electron-deficient alkenes: synthesis of multifunctionalized phosphonopyrazolynes and phosphonopyrazoles |
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Authors: | Maura Marinozzi Silvia Tondi Gloria Marcelli Gianluca Giorgi |
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Affiliation: | 1. Dipartimento di Scienze Farmaceutiche, Università degli Studi di Perugia, Via del Liceo 1, 06123 Perugia, Italy;2. Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Via A. Moro, 53100 Siena, Italy |
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Abstract: | An efficient method for the synthesis of functionalized phosphonopyrazolines has been developed. The procedure involved the microwave-assisted cycloaddition of diisopropyl diazomethylphosphonate to dipolarophiles, such as α,β-unsaturated-nitriles and -esters, performed in neat conditions. By oxidative aromatization the phosphonopyrazolines, thus obtained, were converted into the corresponding phosphonopyazoles. Alternatively, phosphonopyazoles could be obtained by a one-pot, two step procedure directly from dipolarophiles, thus avoiding the isolation of the intermediate pyrazolines. Full spectroscopic characterization of the compounds has been also reported. |
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Keywords: | Phosphorous-containing diazo compounds Phosphonopyrazolines Phosphonopyrazoles 1,3-Dipolar cycloaddition Privileged structures |
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