Cascade polycyclisations in natural product synthesis.

The efficient, stereocontrolled construction of polycyclic ring systems has long presented a formidable challenge to synthetic chemists. Cascade reactions offer a 'quick fix'--building multiple rings in a single step--and often dramatically shorten a synthetic route. In this Emerging Area article, a selection of the most recent and impressive examples of applications of this tactic to natural product synthesis are discussed, which demonstrate the ambition and achievements of the modern synthetic chemist.