Fine Tuning of Quantum Dots Photocatalysts for the Synthesis of Tropane Alkaloid Skeletons**

Abstract

AbstractSeveral types of Quantum Dots (QDs) (CdS, CdSe and InP, as well as core‐shell QDs such as type I InP‐ZnS, quasi type‐II CdSe‐CdS and inverted type‐I CdS‐CdSe) were considered for generating α‐aminoalkyl free radicals. The feasibility of the oxidation of the N‐aryl amines and the generation of the desired radical was evidenced experimentally by quenching of the photoluminescence of the QDs and by testing a vinylation reaction using an alkenylsulfone radical trap. The QDs were tested in a radical [3+3]‐annulation reaction giving access to tropane skeletons and that requires the completion of two consecutive catalytic cycles. Several QDs such as CdS core, CdSe core and inverted type I CdS‐CdSe core‐shell proved to be efficient photocatalysts for this reaction. Interestingly, the addition of a second shorter chain ligand to the QDs appeared to be essential to complete the second catalytic cycle and to obtain the desired bicyclic tropane derivatives. Finally, the scope of the [3+3]‐annulation reaction was explored for the best performing QDs and isolated yields that compare well with classical iridium photocatalysis were obtained.