hide
Free keywords:
-
Abstract:
An introduction is given to the topics of photoredox catalysis and intermolecular radical
difunctionalizations of alkenes. Radical difunctionalizations transform C–C double (multiple)
bonds by generating two new σ bonds in one reaction. Starting from general models in this
research field, applications of α-carbonyl and acyl radicals are described. In addition,
methodologies, which use the consecutive 1,2-addition of a radical as well as a nucleophile are
addressed.
An application of artemisinin as a radical co-initiator in acrylamide polymerizations in aqueous
medium was developed. The assessment of reaction conditions, leading to the formation and
characterization of polymer mixtures is described. Hydrochloric acid as well as iron species are
used as co-initiators. Furthermore, results from an electron paramagnetic resonance (EPR)
experiment with the initiator system were pointing towards the involvement of a by December
2020 unknown radical in the chemistry of artemisinin.
A joined project is discussed, elaborating a method for Brønsted acid catalyzed γ-cyanoketone
formations. The difunctionalization implements α-ketonyl radical formation from condensation of
ketones with tert-butylhydroperoxide3 and methanesulfonyl cyanide.1 Contributions to learn
about the application scope of formed γ-cyanoketones, subsequent transformations and from a
noticed difference in diastereoselectivity compared to the previously reported γ-peroxyketone
synthesis3 are described.
An investigation of photoredox catalyzed alkene difunctionalization using a consecutive addition
of acyl radicals and nucleophilic N-alkylindoles is summarized.2 In the Ir(ppy)3 catalyzed
reaction, simple starting materials, namely aldehydes, N-alkylindoles and styrenes were
employed. Moreover, a base is needed for successful product formation. The reaction is based on
a Ir(III)/Ir(IV) catalytic cycle and tert-butyl perbenzoate as oxidant as well as precursor for tert-
butoxyl radicals. Acyl radicals were generated by hydrogen atom transfer. Aryl as well as
aliphatic aldehydes were suitable substrates. Investigations of the reaction scope, description of
mechanistic indications and discussions the in scientific context are presented.
