Ru(II)-Catalyzed C(sp2)–H Activation Annulation: Synthesis of Fluorescent Benzoisoquinolonyl Acetate/Peptides from N-Arylamides and Ethyne at Room Temperature

Benzoisoquinolones are aryl ring extended isoquinolinone derivatives, constituents of alkaloid natural products. This report describes the synthesis of benzoisoquinolones amino acids/peptides derivatives from respective N-aryl amino esters /peptides through Ru-catalyzed C(sp2)–H annulation at room temperature. Herein, the amino acid ester/amide residue acts as a directing group for annulation at the aryl ring, and then cyclization occurs at the amide NH. Importantly, these benzoisoquinolinones exhibit fluorescence in protic polar solvents. Hence, this methodology could be helpful to transform standard amino ac-ids/peptides into respective fluobenzoisoquinolinones conjugated fluorescent peptide derivatives at room temperature, which could be applicable for leveling amino acid/peptides effectively.