Oxidative functionalization of cyclopentane-1,3-diones: cell imaging studies of diphenothiazine derivatives

This article presents a metal-free expedient approach for simultaneous incorporation of heteroatoms and unsaturation in cyclopentane-1,3-diones via aerial oxidation. We have introduced three distinct methodologies viz. secondary and tertiary amination, dimethylation and diphenothiazine construction (C(sp²)–S bonds) to achieve moderate to high yields. This method is highly scalable and compatible with a wide range of substrates. The photophysical properties of the synthesized fluorescent diphenothiazine derivatives were studied and they were found to exhibit impressive fluorescence. Notably, these compounds are non-cytotoxic and promising candidates for cell imaging studies on breast cancer (MCF-7) cell lines.