Benzylation and alkylation of C(SP3)-H bonds using salts or liquids

Abstract

This thesis comprises of four contributions. First, a comprehensive review of all common directing groups used in C-H functionalisation chemistry is presented. It showcases not only the variety of different methods established from 2015 to 2017, but also highlights advantages and disadvantages of the individual protocols. Therefore it can also be used as a reference book for any synthesis planning.In the next contribution, the use of toluene as benzylating agent in a C-H functionalisation reaction is shown. This radical hetero cross-dehydrogenative coupling with aminopyridines demonstrates that hydrocarbons can displace common benzylation agents like benzyl bromide. This is followed by a research paper, in which gaseous simple olefins are used in C-H alkylation reactions. Those gaseous compounds are not used directly but are formed in situ via Hofmann elimination from the corresponding tetraalkylammonium salts. This approach enables the application of sub-millimolar quantities of the corresponding gas even in stoichiometric amounts. Different directing groups and catalysts are used. The application of a two-chamber system further broadens the scope of this method as separation of olefin generation and the C-H activation enables the possibility to use base sensitive catalysts or substrates.In the last contribution, pyridinium salts are used in benzylation protocol of tetrahydroisoquinolines under photoredox catalysis. The developed method shows the possibility to use such Katritzky salts in C(sp3)-C(sp3) couplings under redox neutral conditions in several examples. In course of this work, the removal of a PMP group from the THIQ moiety is also demonstrated.