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A Liquid–Liquid Biphasic Homogeneous Organocatalytic Aldol Protocol Based on the Use of a Silica Gel Bound Multilayered Ionic Liquid Phase

Authors

  • Dr. Elisa Montroni,

    1. Dipartimento di Chimica “G. Ciamician”, Università degli Studi di Bologna via Selmi 2, 40126, Bologna (Italy)
    2. Consorzio Interuniversitario “C.I.N.M.P.I.S.” via Orabona 4, 70125 Bari (Italy)
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  • Prof. Marco Lombardo,

    Corresponding author
    1. Dipartimento di Chimica “G. Ciamician”, Università degli Studi di Bologna via Selmi 2, 40126, Bologna (Italy)
    • Dipartimento di Chimica “G. Ciamician”, Università degli Studi di Bologna via Selmi 2, 40126, Bologna (Italy)
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  • Dr. Arianna Quintavalla,

    1. Dipartimento di Chimica “G. Ciamician”, Università degli Studi di Bologna via Selmi 2, 40126, Bologna (Italy)
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  • Prof. Claudio Trombini,

    1. Dipartimento di Chimica “G. Ciamician”, Università degli Studi di Bologna via Selmi 2, 40126, Bologna (Italy)
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  • Prof. Michelangelo Gruttadauria,

    Corresponding author
    1. Dipartimento di Scienze e Tecnologie Molecolari e Biomolecolari, Sez. Chimica Organica “E. Paternò”, Università di Palermo viale delle Scienze, Ed. 17, Palermo (Italy)
    • Dipartimento di Scienze e Tecnologie Molecolari e Biomolecolari, Sez. Chimica Organica “E. Paternò”, Università di Palermo viale delle Scienze, Ed. 17, Palermo (Italy)
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  • Dr. Francesco Giacalone

    1. Dipartimento di Scienze e Tecnologie Molecolari e Biomolecolari, Sez. Chimica Organica “E. Paternò”, Università di Palermo viale delle Scienze, Ed. 17, Palermo (Italy)
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Abstract

An innovative two stage liquid–liquid biphasic homogeneous protocol for the asymmetric organocatalytic aldol reaction is proposed, based on the use of the cis-ion-tagged proline 8 dissolved in the liquid film of a multilayered ionic liquid covalently bonded to silica gel 4. The resulting catalytically active material 9 is first soaked with cyclohexanone in the presence of water, resulting in a semi-transparent gel, then the aldehyde is added and the mixture stirred at RT. In the first stage, 4 acts as a catalyst reservoir that delivers 8 to the cyclohexanone phase allowing the reaction to take place homogeneously. In the second stage, cyclohexanone is removed under vacuum and the resulting slurry is extracted with anhydrous diethylether. Now 4 acts as a catalyst sponge, redissolving 8. Product extraction is extremely selective; no trace of catalyst is detected in the product-containing phase, and 9 can be easily reused several times with high cumulative productivity values (up to 523).

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