Chiral rhodium(II)-catalyzed asymmetric aldol-type interception of an oxonium ylide to assemble chiral 2,3-dihydropyrans

A chiral dirhodium complex is an effective and robust catalyst for asymmetric carbene transformations. However, dirhodium-catalyzed asymmetric ylide interception processes are rare, mainly because of the dissociation of the metal catalyst before the stereo-determining step. Herein, we report a chiral dirhodium(II)-catalyzed asymmetric annulation of vinyl diazoesters with α-hydroxyl ketones, which provides an efficient way to form chiral 2,3-dihydropyrans in good yields with excellent diastereos-electivities and enantioselectivities. This article is the first example of the chiral dirhodium complex—controlled asymmetric aldol-type interception of an in situ —formed oxonium ylide. The origin of the high stereoselectivity is well expounded via experimental and computational studies. These generated chiral products exhibit potent antiproliferation activity in three tested cancer cell lines, namely HCT116 (colon cancer), A549 (lung adenocarcinoma), and SJSA-1 (osteosarcoma cancer).