Tandem annulation and dipolar cycloaddition of azomethine imines in catalytic C(sp2)-H functionalization

The synthesis and functionalization of privileged nitrogen heterocycles has emerged as a central topic in drug discovery and material science. In this context, the tandem C-H functionalization and intramolecular annulation has received prodigious attention, as it is able to expedite the construction of heteroaromatic frameworks beyond conventional C-H functionalization. In general, significant effort has been made to develop the [3 + 2] dipolar cycloaddition of azomethine imines with pi-unsaturated compounds. Moreover, the [3 + 3], [4 + 3], [3 + 2 + 2], and [5 + 3] cycloaddition reactions of azomethine imines with various dipolarophiles have been demonstrated. To date, however, the combination of catalytic C-H functionalization and intramolecular cyclization using azomethine imines as both directing groups and dipolar units has been less explored. This review focuses on recent progress toward the catalytic tandem C-H functionalization and dipolar cycloaddition of azomethines imines with a range of coupling partners.

Automated summary

The synthesis and functionalization of privileged nitrogen heterocycles play a central role in drug discovery and material science. Tandem C-H functionalization and intramolecular annulation have gained significant attention for their ability to expedite the construction of heteroaromatic frameworks. While there has been progress in the [3 + 2] dipolar cycloaddition of azomethine imines with pi-unsaturated compounds, the combination of catalytic C-H functionalization and intramolecular cyclization using azomethine imines as both directing groups and dipolar units remains less explored.