Streamlined Synthesis of C(sp3)-Rich N-Heterospirocycles Enabled by Visible-Light-Mediated Photocatalysis.

We report a general visible-light-mediated strategy that enables the construction of complex C(sp3)-rich N-heterospirocycles from feedstock aliphatic ketones and aldehydes with a broad selection of alkene-containing secondary amines. Key to the success of this approach was the utilization of a highly reducing Ir-photocatalyst and orchestration of the intrinsic reactivities of 1,4-cyclohexadiene and Hantzsch ester. This methodology provides streamlined access to complex C(sp3)-rich N-heterospirocycles displaying structural and functional features relevant to fragment-based lead identification programs.