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A Flexible Synthetic Approach to Fluorescent Chromeno[4,3‐ b ]pyridines and Pyrano[3,2‐ c ]chromenes from Electron‐Deficient 3‐Vinylchromones
Author(s) -
Chernov Nikita M.,
Shutov Roman V.,
Sipkidezhda Yu.,
Krivchun Maxim N.,
Yakovlev Igor P.
Publication year - 2021
Publication title -
chempluschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.801
H-Index - 61
ISSN - 2192-6506
DOI - 10.1002/cplu.202100296
Subject(s) - chemistry , ring (chemistry) , combinatorial chemistry , fluorescence , nucleophile , cyanoacetamide , medicinal chemistry , organic chemistry , catalysis , physics , quantum mechanics
We report a flexible approach to the synthesis of phenanthrene‐like heterocycles through organocatalytic ANRORC (Addition of the Nucleophile, Ring Opening, and Ring Closure) reaction of electron‐deficient 3‐vinylchromones with cyanoacetamide. Addition of highly basic DBU (1,8‐diazabicyclo[5.4.0]undec‐7‐ene) or tetramethylguanidine (TMG) at 80 °C leads to chromeno[4,3‐ b ]pyridines in good yields, whereas Et 3 N at 20 °C made it possible to obtain the less accessible pyrano[3,2‐ c ]chromenes and their 2‐imines. The synthesis proceeds in mild conditions (EtOH, 20–80 °C), is versatile and applicable for a wide scope of reactants. The obtained compounds show bright fluorescence in the range 460–595 nm with high quantum yields (up to 0.84) in various solvents (MeCN, DMSO, EtOH, H 2 O).