Synthesis of C6-Substituted Isoquinolino[1,2‑<i>b</i>]quinazolines via Rh(III)-Catalyzed C–H Annulation with Sulfoxonium Ylides

We report the synthesis of C6-substituted isoquinolino­[1,2-b]­quinazolinones via rhodium­(III)-catalyzed C–H annulation with sulfoxonium ylides and evaluation of the cytotoxic activity of the scaffold. This C–H activation approach enables the most straightforward and convergent synthesis of C6-substituted isoquinolino­[1,2-b]­quinazolines reported to date. This operationally simple method is compatible with a wide variety of the sulfoxonium ylide and arene C–H activation coupling partners, permitting access to diverse isoquinolino­[1,2-b]­quinazolines. This method shows a high atom economy, generating H2O and dimethyl sulfoxide (DMSO) as by-products. This method is scalable and operates with exquisite N-lactam cyclization selectivity, thus enabling expedient access to new heterocyclic analogues featuring promising cytotoxic properties.