Many natural abundant and highly bioactive alkaloids contain an indolizidine skeleton.^[1] We developed a straightforward, high yielding methodology to synthesize this scaffold from simple planar N-heterocycles. A wide range of pyridines, quinolines, and isoquinolines react with 2-amino cyclopropane-1,1-dicarboxylates via an ytterbium catalyzed [3+2] annulation reaction to the desired products. They are generally obtained with high diastereoselectivities as trans-isomers. Additionally, we show that the aminal in the products can be easily converted into secondary and tertiary amines through intermediary imine formation followed by reduction or nucleophile addition.

[1] J. P. Michael, Nat. Prod. Rep. 2008, 25, 139-165.