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Internal‐Edge‐Substituted Coumarin‐Fused [6]Helicenes: Asymmetric Synthesis, Structural Features, and Control of Self‐Assembly
Author(s) -
Usui Kazuteru,
Yamamoto Kosuke,
Ueno Yuhei,
Igawa Kazunobu,
Hagihara Ryusuke,
Masuda Toshinobu,
Ojida Akio,
Karasawa Satoru,
Tomooka Katsuhiko,
Hirai Go,
Suemune Hiroshi
Publication year - 2018
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.201803270
Subject(s) - stacking , substituent , coumarin , enantioselective synthesis , heteroatom , conjugated system , chemistry , helix (gastropod) , stereochemistry , crystallography , combinatorial chemistry , polymer , organic chemistry , catalysis , ring (chemistry) , ecology , snail , biology
π‐Conjugated helicenes containing heteroatoms have attracted significant attention due to their diverse chemical and electronic structures, as well as tunable physical properties. It was rationally anticipated that the self‐assembly of coumarin‐fused helicenes would be controlled by the effects of a substituent on the internal edge of the helix. Here, this work reports the efficient syntheses of coumarin‐fused helicenes 1 a , b (R=Ph, Me), and the enantioselective synthesis of 1 a (R=Ph) by chiral Au I ‐catalyzed hydroarylation. The helical structure of 1 was unambiguously determined by X‐ray crystallography. Of particular note, the enantiomerically pure crystal of 1 a adopted a one‐dimensional columnar structure based on π–π stacking interactions, as expected. Furthermore, a significant difference between the fluorescence quantum yields of the enantiomerically pure form and racemate of 1 a was observed.