Synthesis of 3,3-Diarylazetidines by calcium(II)-catalyzed Friedel–Crafts reaction of Azetidinols with unexpected Cbz enhanced reactivity

Azetidines are valuable motifs that readily access under explored chemical space for drug discovery. 3,3-Diarylazetidines are prepared in high yield from N-Cbz azetidinols in a calcium(II)-catalyzed Friedel–Crafts alkylation of (hetero)aromatics and phenols, including complex phenols such as -estradiol. Electron poor phenols undergo O-alkylation. The product azetidines can be derivatized to drug-like compounds through the azetidine nitrogen and the aromatic groups. The N-Cbz group is cru-cial to reactivity by providing stabilization of an intermediate carbocation on the 4-membered ring