A highly efficacious photoinduced reversible complexation-mediated polymerization (photo-RCMP) system using amino alcohol N-oxide as the catalyst has been developed, allowing access to controlled high-molecular-weight polymers of different methacrylates (M n = 497–815 kg/mol, Đ < 1.5), which is very challenging for those known catalytic systems of photo-RCMPs and most organocatalytic photoinduced controlled radical polymerization as it demands higher controllability of catalysts. The monomers can be converted into the polymers nearly quantitatively under simulated or natural sunlight irradiation. Strong hydrogen bond effects are observed in this high-molecular-weight photo-RCMP, in terms of both monomer conversion and molecular weight controllability. The insights of the effects are revealed as the intramolecular hydrogen bond of the N-oxide catalyst modifies the electron density of N-oxide, and thereby facilitates the regeneration of the catalyst (activator) and release of I2 as a predominant effective regulator of radical concentration, by the studies of X-ray analysis, control experiments, density functional theory calculation, ultraviolet–vis absorption spectroscopy, etc.

Both cis- and trans- tetracyclic spiroindolines are the core of many important biologically active indole alkaloids, but the divergent synthesis of these important motifs is largely hampered by the limited stereoselectivity control. A facile stereoinversion protocol is reported here in Michael addition-initiated tandem Mannich cyclizations for constructing tetracyclic spiroindolines, providing an easy access to two diastereoisomeric cores of monoterpene indole alkaloids with high selectivity. The mechanistic studies including in situ NMR experiments, control experiments, and DFT calculations reveal that the reaction undergoes a unique retro-Mannich/re-Mannich rearrangement including a C–C bond cleavage that is very rare for a saturated six-membered carbocycle. Insights into the stereoinversion process have been uncovered, and the major effects were determined to be the electronic properties of N-protecting groups of the indole with the aid of Lewis acid catalysts. By understanding these insights, the stereoselectivity switching strategy is also smoothly applied from enamine substrates to vinyl ether substrates, which are enriched greatly for the divergent synthesis and stereocontrol of monoterpene indole alkaloids. The current reaction also proves to be very practical and was successfully applied to the gram-scale total synthesis of strychnine and deethylibophyllidine in short routes.