Ru(II)-Catalyzed Regiospecific C–H/O–H Oxidative Annulation to Access Isochromeno[8,1-ab]phenazines: Far-Red Fluorescence and Live Cancer Cell Imaging

Abstract

A facile ruthenium(II)-catalyzed regiospecific C–H/O–H oxidative annulation methodology was developed to construct isochromeno[8,1-ab]phenazines. This methodology delivers various advantages, such as scope for diverse substrates, tolerance to a range of functional groups, stability under air, and yields regioselective products. This methodology was successfully applied to synthesize far red (FR) fluorescent probes for live cancer cell imaging. The synthesized compounds displayed notable fluorescence properties in solution and thin-film. Their application in live cancer cell imaging was investigated using various cancer cell lines. The synthesized compound showed prominent FR fluorescence, with high quantum yield, and exhibited better cell-imaging properties, with excellent biocompatibility.

Iridium-Catalyzed Direct C–H Amidation Producing Multicolor Fluorescent Molecules Emitting Blue-to-Red Light and White Light

“…Over the past decades, multicolor fluorescent materials have received extensive attention, because of their potential applications in the next-generation lighting sources and displays, − as well as in optical imaging agents to decipher biological events. − To prepare multicolor fluorescent molecules, chemists have generally synthesized fluorophores from various precursors, or frequently, under different reaction conditions. Sometimes one must use even totally different synthetic pathways, because of a lack of versatility of synthetic scheme.…”

Transition-Metal-Catalyzed C–H Activation Reactions for the Creation and Modification of Organic Fluorophores

“…In 2017, Perumal and co-workers synthesized a series of far red (FR) fluorescent probes, isochromeno[8,1- ab ]phenazine derivatives that displayed exciting fluorescence properties, both in solution phase and in thin films (Scheme 33 ). 131 The obtained fluorophores showed prominent FR fluorescence with high quantum yield, and exhibited better cell imaging properties, with excellent biocompatibility. The regioselective synthesis followed the similar protocol to that depicted in Scheme 32 involving ruthenium(II)-catalyzed C–H activation and subsequent annulation with alkynes.…”

Recent Advances in Ruthenium(II)‐Catalyzed C−H Bond Activation and Alkyne Annulation Reactions

“…It was found that the catalyst could be recovered and used again by adding norbornadiene at the end of the reaction . The Ru(II)‐catalyzed C−H/O−H activation and annulation reactions were also utilized for the synthesis of isochromeno[8,1‐ ab ]phenazines which displayed remarkable fluorescence properties in solution and as a thin film (Scheme ) …”