A series of chiral 2.2paracyclophane(pCp)-derived chromenoisoxazolidines bearing multiple stereocenters were synthesized in good to excellent yields (42%-99%), high diastereoselectivity (>10:1), and excellent enantioselectivity (98.2%-99.9%) through a Yb(OTf)3-catalyzed condensation/(3 + 2) cycloaddition cascade strategy in a one-pot reaction from pCp-derived O-allylated aldehydes and substituted hydroxylamines under mild conditions. Mechanistic studies showed that the planar chirality of paracyclophane scaffold could control the diastereoselectivity of (3 + 2) cycloaddition. The present method features a broad substrate scope, good functional group tolerance, C-C/C-N/C-O bonds and two ring formations in a single operation, high diastereoselectivity and enantioselectivity of multiple stereocenters, and diverse novel paracyclophane derivatives.
Jiao et al. (Sat,) studied this question.