Synthesis of Antitricyclic Morpholine Derivatives through Iodine(III)-Mediated Intramolecular Umpolung Cycloaddition of Olefins

A (diacetoxyiodo)­benzene-mediated
intramolecular cycloaddition
of olefins to construct tricyclic morpholines is presented. A series
of substituted tricyclic morpholines were obtained in one-step simple
operation under mild conditions, and the NMR studies were employed
to see the interaction of reactants. The studies on stereochemistry
showed that transformation of Z-alkene was inhibited,
which is interpreted by density functional theory calculations on Z- and E-transition state models, and only E-alkene resulted in an anticycloaddition product, which
is testified by a single-crystal X-ray diffraction analysis.