Rh-Catalyzed Cycloaddition Cascade of Allenynes and Maleimides: A Powerful Strategy for Constructing Complex
Elias A Romero-Cavagnaro1, Albert Artigas1, Anna Pla-Quintana1
1Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona (UdG), Facultat de Ciències, C/Maria Aurèlia Capmany, 69, 17003 Girona, Catalunya, Spain.
None:
Herein, we report that 1,5- and 1,6-allenynes react with two equivalents of maleimide to afford pentacyclic frameworks featuring a bicyclo[2.2.2]octene core in a fully diastereoselective fashion. DFT calculations and deuterium-labeling studies reveal an unconventional mechanism initiated by a noncanonical [2 + 2 + 2] cycloaddition that, through intramolecular hydrogen shifts, diverges from the classical pathway to generate a conjugated diene. A subsequent thermal Diels-Alder reaction with a second maleimide completes the cascade, unveiling a distinct reactivity mode.
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