A thesis submitted to the Faculty of Science University of the Witwatersrand Johannesburg In fulfilment of the requirements for the Degree of Doctor of Philosophy June 2015 / The first two chapters of this thesis deals with the synthesis of 6H-benzo[d]-naphtho[ 1,2- b]pyran-6-one motif found in gilvocarcin as well as related aromatic compounds containing the aromatic pyranone moiety. The synthesis was undertaken by employing the Suzuki- Miyaura cross coupling reaction and a novel N-bromosuccinimide induced ring cyclization reaction to afford the pyranone. It was established that the treatment of both [2-(1,4- dimethoxynaphthalen-2-yl)phenyl]methanol and (2',5'-dimethoxy-[1,1'-biphenyl]-2- yl)methanol separately with N-bromosuccinimide results in the unexpected synthesis of a naphthopyranone ring system in the form of 12-methoxy-6H-dibenzo[c,h]chromen-6-one and 2-methoxy-6H-benzo[c]chromen-6-one respectively. Application of the same methodology for the attempted synthesis of related compounds namely, 1-hydroxy-12-methoxy-6Hdibenzo[ c,h]chromen-6-one and 8-fluoro-12-methoxy-6H-dibenzo[c,h]chromen-6-one unfortunately did not generate the desired results. Attempts were made to elucidate the mechanism of this reaction. The most apparent mechanism indicates that Nbromosuccinimide, in the presence of air, oxidizes the benzylic alcohol to an aldehyde which is then converted to an acid bromide allowing for the ring closure with the adjacent aromatic ether to afford the desired pyranone. In Chapter 3 and 4 of this thesis we dealt with the synthesis of benzo[b]phenanthridine-7,12- dione motif, the backbone of biologically important secondary metabolite jadomycin B. Again, a key step involves employing the Suzuki-Miyaura cross coupling reaction. The synthetic methodology also sheds some light on the dynamics of the ring closure of benzylic amines onto naphthoquinones resulting in the synthesis of benzo[i]phenanthridine-11,12- dione, 12-methoxybenzo[i]phenanthridine and 1-hydroxybenzo[i]phenanthridine-11,12-dione. The synthesis of benzo fused phenanthridines has been undertaken in Chapter 5 and 6 by employing Suzuki-Miyaura cross coupling reaction and a potassium t-butoxide and light mediated cyclization reaction as the key steps. The synthesis of 5- phenylbenzo[i]phenanthridine was undertaken successfully but attempts to execute the same methodology to form a compound library of related benzo-fused phenanthridines was unsuccessful. The same methodology employing a Suzuki-Miyura cross coupling reaction and potassium tbutoxide and light mediated cyclization reaction was applied in Chapter 7 and 8 of the thesis directed towards the synthesis of 13H-indolo[3,2-c]acridine and 3-methoxy-13H-indolo[3,2- c]acridine. The successful synthesis of the 13H-indolo[3,2-c]acridine is reported using this methodology.