Pd(II)-Catalyzed Oxidative Annulation via Double C–H Activations: Synthesis and Photophysical Properties of Bis-Coumarins

Abstract

A Pd­(II)-catalyzed oxidative annulation reaction of 4-hydroxycoumarin and arylcarboxylic acid via double C–H bond activations has been accomplished for the synthesis of bis-coumarins. This synthetic strategy provides a wide range of structurally diversified bis-coumarins in moderate to good yields with a variety of functional group compatibility. Moreover, photophysical properties of synthesized bis-coumarins have been evaluated, which reveals their interesting fluorescent properties.

Synthesis and luminescence properties of functionalized V-shaped bis-coumarin derivatives

“…[26][27][28][29] Among the various heterocycle-fused coumarins, coumarin-fused coumarins have attracted strong attention due to their broad spectrum pharmacological, photoelectronic and optical properties. [30][31][32][33] In 2014, Tasior and co-workers 30 reported a series of V-shaped biscoumarins and their photophysical properties, some of which exhibited strong green-yellow emission and acceptable Stokes shifts, indicating that these V-shaped bis-coumarins hold great potential in photonics-related applications. Compared with simple coumarins possessing one coumarin skeleton, V-shaped bis-coumarins have a larger rigid conjugated plane and higher fluorescence quantum yields, making the charge transfer within the molecule more effective and their photophysical properties superior to those of mono-coumarins.…”

Sensing and sensitive visualization of latent fingerprints on various surfaces using a versatile fluorescent aggregation‐induced emission‐based coumarin derivative

“…Coumarin derivatives are important oxygen heterocycles in organic chemistry due to their natural occurrence, low toxicity, flexible nature and biological significance. [1,2] Many oxygen heterocycles both naturally occurring and synthetic molecules exhibit excellent biological and pharmacological activities as anticancer reagents (Taxol), [3] for congestive heart failure (CHF) treatment (digoxin), [4] as immunosuppressants (cyclosporin A) or hypolipidemics (lovastatin), [2] or for antimicrobial, [5] anti-inflammatory, [6] and antioxidant activities. [7][8][9] As coumarin derivatives show excellent photophysical properties, coumarins are used in various electroluminescence fields for example as optical brighteners, laser dyes, or OLED.…”

Indane-Fused Spiropentadiene Chromanones: A Pd-Catalyzed Spiroannulation Followed by Cyclization via C–H Activation Strategy

“…Although the reported methodologies have gained significant progress, further improvement in the synthesis of complex polycyclic systems is highly demanded in this field. Palladium-catalyzed C–S bond activation of bromothiophenes and our research work on coumarin moiety encouraged us to design a new Pd-catalyzed cascade strategy followed by C–H activation for the synthesis of indane-fused spiropentadiene chromanones from 4-bromocoumarins and alkynes (Scheme d). This method offers the privilege to form a sterically congested spirocyclic core via multiple bond formation pathways, providing a broad range of spirocyclic analogues.…”