ChemInform Abstract: Rhodium‐Catalyzed Cycloaddition of Carbonyl Ylides for the Synthesis of Spiro[furo[2,3‐a]xanthene‐2,3′‐indolin]‐2′‐one Scaffolds.

Abstract

An intramolecular cycloaddition of oxonium ylides generated from 3-diazooxindole and a bifunctional substrate i.e. 2-methyl-2-(4-methylpent-3-en-1-yl)-2H-chromene-3-carbaldehyde has been achieved using 5 mol% of Rh2(OAc)4 to produce highly substituted 3,3,5a-trimethyl-3a,5,5a,11b-tetrahydro-3H,4H-spiro[furo[2,3-a]xanthene-2,3′-indolin]-2′-ones in good yields with high diastereoselectivity. This is the first example of the synthesis of biologically relavant polycyclic frameworks from readily accessible precursors.