Modulation of the complex reactivity of cyclohexenylidene malononitriles using diverse beta-aryl-substituted enals and proper organocatalytic modalities resulted in divergent asymmetric reaction patterns to furnish angularly fused or bridged carbabicyclic frameworks. In particular, use of remotely enolizable dicyanodienes 1, under one-pot sequential amine/NHC catalysis, led to [3 + 2] cycloaddition to afford epsilon,delta-bonded spiro[4.5]decanone structures 5. Alternatively, modifying the standard amine catalysis by adding a suitable chemical stimulus (p-nitrophenol cocatalyst) switched the reactivity decidedly toward a domino [4 + 2] cycloaddition to afford gamma',delta-bonded bicyclo[2.2.2]octane carbaldehydes 8. Products invariably formed in good yields, with rigorous chemo-, regio-, diastereo-, and enantiocontrol. Experimental evidences, including carbon isotope effects measured by 13C NMR, were indicative of the rate (and stereochemistry) determining step of these transformations and suggested a stepwise mechanism for the [4 + 2] cycloadditive pathway.

Exploring the Vinylogous Reactivity of Cyclohexenylidene Malononitriles: Switchable Regioselectivity in the Organocatalytic Asymmetric Addition to Enals Giving Highly Enantioenriched Carbabicyclic Structures / L., Dell’Amico; G., Rassu; V., Zambrano; Sartori, Andrea; Curti, Claudio; Battistini, Lucia; Pelosi, Giorgio; Casiraghi, Giovanni; Zanardi, Franca. - In: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY. - ISSN 0002-7863. - 136:(2014), pp. 11107-11114. [10.1021/ja5054576]

Exploring the Vinylogous Reactivity of Cyclohexenylidene Malononitriles: Switchable Regioselectivity in the Organocatalytic Asymmetric Addition to Enals Giving Highly Enantioenriched Carbabicyclic Structures

SARTORI, Andrea;CURTI, Claudio;BATTISTINI, Lucia;PELOSI, Giorgio;CASIRAGHI, Giovanni;ZANARDI, Franca
2014-01-01

Abstract

Modulation of the complex reactivity of cyclohexenylidene malononitriles using diverse beta-aryl-substituted enals and proper organocatalytic modalities resulted in divergent asymmetric reaction patterns to furnish angularly fused or bridged carbabicyclic frameworks. In particular, use of remotely enolizable dicyanodienes 1, under one-pot sequential amine/NHC catalysis, led to [3 + 2] cycloaddition to afford epsilon,delta-bonded spiro[4.5]decanone structures 5. Alternatively, modifying the standard amine catalysis by adding a suitable chemical stimulus (p-nitrophenol cocatalyst) switched the reactivity decidedly toward a domino [4 + 2] cycloaddition to afford gamma',delta-bonded bicyclo[2.2.2]octane carbaldehydes 8. Products invariably formed in good yields, with rigorous chemo-, regio-, diastereo-, and enantiocontrol. Experimental evidences, including carbon isotope effects measured by 13C NMR, were indicative of the rate (and stereochemistry) determining step of these transformations and suggested a stepwise mechanism for the [4 + 2] cycloadditive pathway.
2014
Exploring the Vinylogous Reactivity of Cyclohexenylidene Malononitriles: Switchable Regioselectivity in the Organocatalytic Asymmetric Addition to Enals Giving Highly Enantioenriched Carbabicyclic Structures / L., Dell’Amico; G., Rassu; V., Zambrano; Sartori, Andrea; Curti, Claudio; Battistini, Lucia; Pelosi, Giorgio; Casiraghi, Giovanni; Zanardi, Franca. - In: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY. - ISSN 0002-7863. - 136:(2014), pp. 11107-11114. [10.1021/ja5054576]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11381/2744700
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