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Reusable Silica‐Supported Ammonium BINSate Catalysts for Enantio‐ and Diastereoselective Friedel–Crafts‐Type Double Aminoalkylation of N ‐Alkylpyrroles with Aldimines
Author(s) -
Hatano Manabu,
Zhao Xue,
Mochizuki Takuya,
Maeda Kyogo,
Motokura Ken,
Ishihara Kazuaki
Publication year - 2021
Publication title -
asian journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.846
H-Index - 44
eISSN - 2193-5815
pISSN - 2193-5807
DOI - 10.1002/ajoc.202000603
Subject(s) - aldimine , chemistry , catalysis , friedel–crafts reaction , organocatalysis , organic chemistry , pyrrole , brønsted–lowry acid–base theory , enantioselective synthesis
Silica‐supported ammonium ( R )‐BINSate catalysts for the enantio‐ and diastereoselective Friedel–Crafts‐type double aminoalkylation of N ‐benzyl‐ or N ‐methylpyrrole with aldimines were developed. The present heterogeneous catalysts showed high catalytic activity compared to our previous homogeneous ( R )‐BINSA ammonium catalysts, which were effective for single aminoalkylation. Simple aldimines could be used, and the corresponding pyrrole‐derived chiral C 2 ‐symmetric triamines were obtained in the dl ‐form with good to extremely high enantioselectivities. The heterogeneous catalyst could be easily recovered and reused three times without any loss of catalytic activity or enantiocontrol. An XPS analysis supported precise preparation of the catalysts in situ and with good quality after recycling three times. From the perspective of modern green chemistry with fine asymmetric organocatalysis, the development of such chiral strong Brønsted acid catalysts might be useful for both laboratory and industrial applications.