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Helquats as Promoters of the Povarov Reaction: Synthesis of 1,2,3,4‐Tetrahydroquinoline Scaffolds Catalyzed by Helicene‐Viologen Hybrids
Author(s) -
ReyesGutiérrez Paul E.,
Amatov Tynchtyk T.,
Švec Pavel,
Císařová Ivana,
Šaman David,
Pohl Radek,
Teplý Filip,
Pospíšil Lubomír
Publication year - 2020
Publication title -
chempluschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.801
H-Index - 61
ISSN - 2192-6506
DOI - 10.1002/cplu.202000151
Subject(s) - viologen , helicene , catalysis , ferrocene , chemistry , redox , electron transfer , combinatorial chemistry , radical ion , substrate (aquarium) , photochemistry , electrochemistry , organic chemistry , ion , molecule , oceanography , electrode , geology
Helquats (HQs) are structurally linked to helicenes and viologens, and they represent an attractive field of research in chemistry and medicinal chemistry. In the present work they were used as catalysts for the synthesis of 1,2,3,4‐tetrahydroquinolines in good yields by the Povarov reaction. The substrate scope and the capability of different helquats to promote Povarov reactions are demonstrated. Studies to elucidate mechanistic details revealed that helquats act as single‐electron transfer oxidants through a cation‐radical mechanism. The screening of the catalytic activity of HQs confirmed that an active HQ must have a LUMO energy below −8.67 eV and the standard redox potential higher (less negative) than −1.2 V vs. the ferrocene/ferrocenium redox couple.