Nitrene transfer chemistry is an effective strategy for introducing C–N bonds, which are ubiquitous in pharmaceuticals, agrochemicals and diverse bioactive natural products. The development of chemical methodology that can functionalize unique sites within natural products through nitrene transfer remains a challenge in the field. Herein, we developed copper catalyzed chemoselective allylic C–H amination and catalyst-free visible-light induced aziridination of alkenes through nitrene transfer. In general, both reactions tolerate a wide range of functional groups and occur with predictable regioselectivity. Furthermore, combination of these two methods enable the intermolecular chemo-selective late-stage amination of biologically active natural products, leading to C–H amination or C=C aziridination products in a tunable way. A series of control experiments indicate two-step radical processes were involved in both reaction systems.
A late-stage functionalization
(LSF) of the natural product andrographolide
for the efficient assembly of a range of structurally interesting
and diverse tricyclic-aza derivatives was developed. The key to the
diversification is a photo-catalyzed intramolecular hydroamination
reaction, and acridinium derivatives were demonstrated to be the optimal
catalysts. Additionally, the synthesized tricyclic aza-andrographolide
derivatives were found to inhibit human coronavirus with high potency.
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