Synthesis of Spiro[benzo[<i>d</i>][1,3]oxazine-4,4′-isoquinoline]s via [4+1+1] Annulation of <i>N</i>-Aryl Amidines with Diazo Homophthalimides and O<sub>2</sub>
Qianting Zhou, Xia Song, Xinying Zhang, Xuesen Fan
Abstract
Synthesis of spiro[benzo[d][1,3]oxazine-4,4′-isoquinoline]s through a unique [4+1+1] annulation of N-aryl amidines with diazo homophthalimides and O2 is presented. This unprecedented spirocyclization reaction features readily obtainable substrates, structurally and pharmaceutically attractive products, a cost-free and clean oxygen source, sustainable reaction medium, tolerance of a broad spectrum of functional groups, and an interesting reaction mechanism based on sequential C(sp2)–H/C(sp3)–H bond cleavage and oxygen insertion.
Topics & Concepts
ChemistryIsoquinolineAnnulationDiazoBond cleavageArylCleavage (geology)Medicinal chemistryStereochemistryCombinatorial chemistryOrganic chemistryCatalysisFracture (geology)EngineeringAlkylGeotechnical engineeringCatalytic C–H Functionalization MethodsCyclopropane Reaction MechanismsSynthesis and Catalytic Reactions