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Asymmetric Aza‐Diels–Alder Reaction with Ion‐Paired—Iron Lewis Acid—Brønsted Acid Catalyst
Author(s) -
Tomifuji Rei,
Kurahashi Takuya,
Matsubara Seijiro
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201901563
Subject(s) - chemistry , catalysis , phosphoric acid , lewis acids and bases , brønsted–lowry acid–base theory , lewis acid catalysis , diels–alder reaction , medicinal chemistry , polymer chemistry , photochemistry , organic chemistry
The development and use of a multiple‐activation catalyst with ion‐paired Lewis acid and Brønsted acid in an asymmetric aza‐Diels–Alder reaction of simple dienes (non‐Danishefsky‐type electron‐rich dienes) was achieved by utilizing the [FeBr 2 ] + [FeBr 4 ] − combination prepared in situ from FeBr 3 and chiral phosphoric acid. Synergistic effects of the highly active ion‐paired Lewis acid [FeBr 2 ] + [FeBr 4 ] − and a chiral Brønsted acid are important for promoting the reaction with high turnover frequency and high enantioselectivity. The multiple‐activation catalyst system was confirmed using synchrotron‐based X‐ray absorption fine structure measurements, and theoretical studies. This study reveals that the developed catalyst promoted the reaction not only by the interaction offered by the ion‐paired Lewis acid and the Brønsted acid but also noncovalent interactions.