title: Polycyclic Ring Formation Using Bis-diazolactams for Cascade Stitching.
abstract: The chemoselective reaction of donor/acceptor (D/A) and acceptor/acceptor (A/A) diazo moieties in the same molecule was examined using 3-diazo-1-(ethyl 2-diazomalonyl)indolin-2-one under rhodium(II) catalysis. The metallo carbenoid derived from the D/A diazo group is preferentially formed and undergoes selective CH, NH, and OH insertion reactions, cyclopropanation, cyclopropenation, sulfur ylide formation/2,3-sigmatropic rearrangement, as well as nitrogen ylide formation followed by azetidine ring expansion. The initial reaction can be paired with a subsequent tandem cascade sequence involving dipole formation/cycloaddition in either an intra- or intermolecular sense to generate polycyclic N-heterocycles in one pot, with the formation up to three new rings in a single operation. Excellent diastereoselectivity was observed in the intramolecular cycloaddition reaction producing 5 to 7-membered rings.
authors.affiliation: Department of Chemistry, Emory University , Atlanta, Georgia 30322, United States.
authors.forename: Sara A
authors.initials: SA
authors.lastname: Bonderoff
authors.affiliation: Department of Chemistry, Emory University , Atlanta, Georgia 30322, United States.
authors.forename: Albert
authors.identifier: 0000-0001-7323-8106
authors.initials: A
authors.lastname: Padwa