A versatile access to new halogenated 7-azidocoumarins for photoaffinity labeling: Synthesis and photophysical properties

A versatile methodology for the synthesis of 6/8-halogenated 7-aminocoumarins from the corresponding 7-hydroxy analogs using Pd-catalyzed amination reaction as the key step is presented. Further readily conversion into 7-azidocoumarins was performed and the resulting aryl azides proved higher stability and reactivity than the corresponding non-halogenated parent compound. These new compounds may thus constitute attractive scaffolds for designing novel photoaffinity reagents for various challenging bio-labeling applications.

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► A novel synthetic approach to the preparation of pro-fluorescent 7-azidocoumarins.
► The use of a Buchwald–Hartwig amination reaction as the key step.
► A beneficial effect of ortho halogen atom in the stability of 7-azidocoumarins.
► No effect of ortho halogen atom on fluorescence properties of 7-aminocoumarins.