Catalytic asymmetric construction of spiro pyrrolidines with contiguous quaternary centers via 1,3-dipolar cycloaddition of azomethine ylides

Bioactive 5-aza-spiro[2,4]heptanes with high functionality and up to three contiguous all-carbon quaternary stereogenic centers were synthesized by Cu(I)-catalyzed asymmetric endo-selective 1,3-dipolar cycloaddition of azomethine ylides with cyclopropylidene acetates. This synthesis system performs well for a broad scope of substrates. α-unsubstituted/α-substituted azomethine ylides and cyclopropylidene acetates are compatible 1,3-dipoles and dipolarophiles, which afford the spiro heterocycles with contiguous quaternary centers at 2-, 3- and 4-positions of the pyrrolidine ring in good yield (up to 97%) and high diastereoselectivity (95:5–>98:2 d.r) and excellent enantioselectivity (87%–98% ee).

Graphical AbstractBioactive 5-aza-spiro[2,4]heptanes with high functionality and up to three contiguous all-carbon quaternary centers were synthesized by Cu(I)-catalyzed asymmetric endo-selective 1,3-dipolar cycloaddition of azomethine ylides with cyclopropylidene acetates.Figure optionsDownload as PowerPoint slide