A Flexible Synthetic Approach to Fluorescent Chromeno[4,3-b]pyridines and Pyrano[3,2-c]chromenes from Electron-Deficient 3-Vinylchromones

Nikita M Chernov; Roman V Shutov; Nadezhda Yu Sipkina; Maxim N Krivchun; Igor P Yakovlev

doi:10.1002/cplu.202100296

A Flexible Synthetic Approach to Fluorescent Chromeno[4,3-b]pyridines and Pyrano[3,2-c]chromenes from Electron-Deficient 3-Vinylchromones

Chempluschem. 2021 Aug 19;86(9):1256-1266. doi: 10.1002/cplu.202100296. Online ahead of print.

Authors

Nikita M Chernov¹, Roman V Shutov¹, Nadezhda Yu Sipkina², Maxim N Krivchun³, Igor P Yakovlev¹

Affiliations

¹ Organic Chemistry Department, Saint-Petersburg State Chemical Pharmaceutical University, Prof. Popov st., 14, Saint-Petersburg, 197376, Russia.
² Analytical Center, Saint-Petersburg State Chemical Pharmaceutical University, Prof. Popov st., 14, Saint-Petersburg, 197376, Russia.
³ Organic Chemistry Department, Saint-Petersburg State Institute of Technology, Moskovsky av., 26, Saint-Petersburg, 190013, Russia.

PMID: 34472730
DOI: 10.1002/cplu.202100296

Abstract

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 Et₃ 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, H₂ O).

Keywords: cyanoacetamide; fluorescence; heterocycles; organocatalysis; vinylchromone.

Abstract

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