Cascade C–H Activation/Annulation of Sulfoxonium Ylides with Vinyl Cyclopropanes: Access to Cyclopropane-Fused α-Tetralones

Abstract

Rh-catalyzed weak and traceless directing-group-assisted cascade C− H activation and annulation of sulfoxonium ylides with vinyl cyclopropanes as a coupling partner have been accomplished to furnish functionalized cyclopropanefused tetralones at moderate temperature. The C−C bond formation, cyclopropanation, functional group tolerance, late-stage diversifications of drug molecules, and scale-up are the important practical features.

Rh-Catalyzed Annulation of Enaminones with Maleimides for Functionalized Aza-spiro α-Tetralones and Benzo[e]isoindoles via C–H Activation/C═C Bond Cleavage

“…Among them, the most typical method includes Friedel–Crafts reactions between arenes and succinic anhydride followed by a sequential reduction and a further intramolecular Friedel–Crafts reaction . Other methods include the oxidation of tetralin, the AlCl 3 -catalyzed acylation of benzene with γ-butyrolactone, the transition-metal-catalyzed annulation of sulfoxonium ylides and ring expansion of tertiary cyclobutanols . In contrast, only a few synthetic approaches are available for the preparation of spiro-fused α-tetralones.…”

Expedient C–H allylation of sulfoxonium ylides: merging C–H and C–C/C–het bond activation

“…4 Furthermore, efforts have been made to explore the reactivity of sulfoxonium ylides for cascade C–H activation and annulation with unsaturated coupling partners and vinyl cyclopropanes (VCPs) in the presence of Rh-catalysis (Scheme 1a). 5 Correspondingly, the formation of C–C and C–hetero bonds at the C(olefinic)–H of sulfoxonium ylides has been widely studied. 6 Despite this progress, C–H activation of weak chelation-assisted sulfoxonium ylides and ring-opening of strained vinyl carbo-/heterocycles 7 using less expensive Co-catalysis remains largely underexplored.…”