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.We are grateful to the Gates Cambridge Trust (N.J.F.) and Herchel Smith Scholarship Scheme (A.T.) for studentships, the EPSRC (EP/S020292/1 and EP/N031792/1), Ambitious Leader’s Program, Hokkaido University, Japan (Y.K.), and the Royal Society for a Wolfson Merit Award (M.J.G.). S.M.W. is a Fellow of the AstraZeneca Postdoctoral program. We are grateful to the EPSRC UK National Mass Spectrometry Facility at Swansea University for HRMS analysis