Organocatalytic Asymmetric Friedel-Crafts Reaction of Prochiral 3,4-Fused Pyrroles via a Desymmetrization/Kinetic
Rupkumar Khuntia1, Sujan Sarkar1, Ankita Roy1
1Department of Chemistry, Indian Institute of Technology Guwahati, North Guwahati, Assam 781039, India.
Abstract:
An intriguing but underexplored topic is the central chirality in heteroarene derivatives originating from unsymmetrically substituted heteroarene rings. Herein, we demonstrate the first catalytic enantioselective Friedel-Crafts reaction of prochiral 3,4-fused pyrroles. Allenamides are used as the electrophiles, and an easily available phosphoric acid was employed as the catalyst. Desymmetrization and kinetic resolution, two asymmetric processes, were used successively to produce polycyclic 2-substituted, 3,4-fused pyrroles with high enantioselectivities (up to 98:2 er). Also, the products were elaborated into synthetically challenging chiral isoindole compounds.
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