부산대학교 도서관

Selective metal-free functionalisation of aromatic C-H bonds is a valuable goal in organic synthetic chemistry. Recently it has been shown that Pummerer-type reactions, for example interrupted Pummerer reactions, can be used to trap nucleophiles and deliver them selectively to aromatic rings via [3,3]-sigmatropic rearrangements. This thesis investigates the utility of sulfoxide-directed metal-free C-H functionalisations in the synthesis and derivatisation of a range of benzothiophene scaffolds. Through a sequence involving metal-free aromatic propargylation reactions and novel, diversity introducing heterocyclisations, benzothiophenes possessing a range of functionality, namely ketone, alkane or alkene substituents, can be synthesised. The value of this new cyclisation protocol is demonstrated through the sysnthesis of different highly conjugated benzothiophene motifs, molecules of particular interest in organic electronics. Using alkene substituted benzothiophenes; a new, iodine-mediated route to highly conjugated benzodithiophene cores is reported along with the application of two-directional heterocyclisations allowing the synthesis of naphthodithiophene scaffolds. Finally, selective C3 arylation and alkylation of benzothiophenes is reported through the use of benzothiophene S-oxides, an underexplored class of organic compound. Oxidation of the sulfur atom intrinsic to benzothiophene molecules allows the capture of phenol, propargyl silane and allyl silane coupling partners, which are delivered with complete regio-selectivity to the C3 position of the benzothiophene.