Recent trends in catalytic sp3 C-H functionalization of heterocycles.

Heterocycles are a ubiquitous substructure in organic small molecules designed for use in materials and medicines. Recent work in catalysis has focused on enabling access to new heterocycle structures by sp3 C-H functionalization on alkyl side-chain substituents-especially at the heterobenzylic position-with more than two hundred manuscripts published just within the last ten years. Rather than describing in detail each of these reports, in this mini-review we attempt to highlight gaps in existing techniques. A semi-quantitative overview of ongoing work strongly suggests that several specific heterocycle types and bond formations outside of C-C, C-N, and C-O have been almost completely overlooked.