Synthesis of heterobicyclo[n.1.1]alkanes.

Heterocyclic bicyclo[n.1.1]alkanes have emerged as important scaffolds in contemporary drug design due to their rigid frameworks that enable the positioning of their subsituents along well defined vectors in chemical space. Offering much potential as alternative cores to traditional benzene rings, heterobicyclo[2.1.1]hexanes (HBCHexs) and heterobicyclo[3.1.1]heptanes (HBCHeps) in particular have attracted significant attention from the synthetic community. A plethora of methods have recently been developed to access these useful motifs, using both radical and polar strategies to forge the bicyclic system. This review discusses recent developments in the field, with a focus on mechanistic aspects, and those methodologies that show the most potential for general application.