Synergistic [4 + 1] Spiroannulation and Selective Ring-Opening Strategy toward γ-Spirolactams.

A unique and propitious [4 + 1] spiroannulation of 2-aryl-4-benzo[][1,3]oxazine with maleimide has been delineated, furnishing diversely embellished γ-spirolactams featuring pendant benzyl alcohol via Rh(III)-catalyzed consecutive ring closing/ring opening followed by regioselective cleavage of the C4-O bond of 1,3-benzoxazine promoted by an generated water maneuver constructing new C-C, C-N, and C-O bonds at a go. A detailed mechanistic study, including a thorough analysis of the incorporation of an extra oxygen source, has been showcased to make this strategy for structurally orchestrated isoindoline-1-one spirosuccinimides.

[3+2] Cascade Ring-Closing/Ring-Opening Strategy: Access to -Indene-Tethered Amino Alcohols.

An unprecedented atom-economic redox neutral regioselective Rh(III)-catalyzed cascade [3+2] annulation of 2-aryl oxazoline with α,β-unsaturated nitro olefins has been accomplished, furnishing a novel set of nitro-functionalized indene-tethered amino alcohols through a synergistic ring-closing/ring-opening strategy via the formation of two new C-C bonds and the regioselective cleavage of the C2-O bond of oxazoline under silver free mild reaction conditions with a broad substrate scope.

Electrochemical C(sp)-C(sp) cross-dehydrogenative coupling: enabling access to 9-substituted fluorescent acridanes.

A straightforward strategy for direct access of C9-functionalized -alkyl-acridanes in good to excellent yields has been established a metal- and external oxidant-free sustainable electrochemical C(sp)-C(sp) cross-dehydrogenative coupling reaction between acridanes and benzo fused lactones at ambient temperature. A broad substrate scope with superior functional-group tolerance anodic oxidation of acridanes permitted the synthesis of a vast spectrum of fluorescence-active acridanes with high quantum yields.

Synthesis of indene-fused spiro-dibenz(ox)azepines Rh(III)-catalyzed cascade regioselective C-H activation/annulation.

We report an unprecedented atom-economic one-pot Cp*Rh(III)-catalyzed regioselective [3+2]-spiroannulation reaction between dibenz(ox)azepines and ynones, allowing the synthesis of biologically relevant novel spirocyclic dibenz(ox)azepines under operationally simple and mild reaction conditions. The reaction proceeds without any silver additive or external oxidant implementing a redox-neutral pathway. A broad substrate scope with diverse functional group tolerance permitted the regioselective synthesis of a wide spectrum of indene-containing spirocyclic dibenz(ox)azepines in good to excellent yields.

Regio- and Diastereoselective [3 + 2]-Spiroannulation of Benzoxazines with Chalcones: A Rh(III)-Catalyzed Redox-Neutral Approach to α-Aroyl Spiro-Indanamines.

We report an atom-economic Rh(III)-catalyzed [3 + 2]-spiroannulation reaction between cyclic ketimines and α,β-unsaturated carbonyl compounds, allowing the synthesis of novel spirocycles with concomitant generation of three stereogenic centers in one pot. The reaction does not require any silver additives or external oxidants and is believed to proceed in a redox-neutral manner. A broad substrate scope with good functional group tolerance permitted the synthesis of a vast spectrum of spirocyclic 1,4-benzoxazine derivatives containing polysubstituted α-aroyl-indanamines in good to excellent yields with high diastereoselectivity.