Medium-Ring Effects on the Endo/Exo Selectivity of the Organocatalytic Intramolecular Diels-Alder Reaction
Joel F Hooper1, Natalie C James2, Esra Bozkurt3
1School of Chemistry, Bio21 Institute, The University of Melbourne , 30 Flemington Road, Melbourne, Victoria 3010, Australia.
Abstract:
The intramolecular Diels-Alder reaction has been used as a powerful method to access the tricyclic core of the eunicellin natural products from a number of 9-membered-ring precursors. The endo/exo selectivity of this reaction can be controlled through a remarkable organocatalytic approach, employing MacMillan's imidazolidinone catalysts, although the mechanistic origin of this selectivity remains unclear. We present a combined experimental and density functional theory investigation, providing insight into the effects of medium-ring constraints on the organocatalyzed intramolecular Diels-Alder reaction to form the isobenzofuran core of the eunicellins.
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