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Design and Synthesis of Bridging Chiral p–t ‐Butylcalix[4]arene Tetrahydroisoquinolines and Their Application in Henry Reaction as Chiral Organocatalysts
Author(s) -
Ma Hao,
He Yong,
Weng XiuFang,
Tang ShengAn,
Yan JiuXing,
Li ShaoYong,
Dong WeiLi,
Ma ShiKun
Publication year - 2019
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201900859
Subject(s) - catalysis , chemistry , stereoselectivity , amine gas treating , yield (engineering) , chloroacetyl chloride , nitroaldol reaction , stereochemistry , chloride , bridging (networking) , medicinal chemistry , enantioselective synthesis , organic chemistry , materials science , metallurgy , computer network , computer science
A pair of bridging chiral p‐t ‐butylcalix[4]arenes ( 2a and 2b ) (were) synthesized from 1 through homologous anionic ortho ‐Fries rearrangement, and optically resolved with (1 S )‐(+)‐10‐camphorsulfonyl chloride as chiral auxiliary. Bridging chiral p‐t‐ butylcalix[4]arene tetrahydroisoquinolines ( 9a and 9b ) as chiral organocatalysts for Henry reaction were designed and synthesized through the structural modification of 2a and 2b , respectively. Compared to the catalytic enantioselectivity of the unmodified tertiary amine ( 4b : ∼0% ee and 63% yield), those of the tetrahydroisoquinoline derivatives ( 9b : up to 13.4% ee and 96% yield) were distinctly enhanced. Although the increase magnitude of the catalytic ee is not remarkable, these catalytic results prove that the conformation inversion of calix[4]arene skeleton and the rotational freedom reduction of catalytic amine group indeed bring beneficial effects on the catalytic stereoselectivity.