A Two-Step Synthesis of 2-Spiropiperidines.

A general two-step synthesis of 2-spiropiperidines has been developed. delta-Amino-b-ketoesters can be reacted with cyclic ketones to generate 2-spiropiperidines in good to excellent yields. The 2-spiropiperidines formed occupy an under-explored region of 3D-chemical space and are novel scaffolds for use in drug discovery programs. These 2-spiropiperidines can be further functionalised to generate small highly sp3-rich structures, which exhibit an excellent likeness to lead-molecules in drug discovery.