Methodological and comparative studies on directed ortho metallation of aryl tert-butyl sulfoxides and Ni(0)-catalyzed cross-coupling of aryl triflates and O-aryl carbamates. Studies directed toward the total synthesis of sterigmatocystin

Chapter 1. The tert-butyl sulfoxide group has been demonstrated as an efficient director of ortho lithiation. A variety of electrophiles were shown to be successfully employed in the reaction, providing 2-disubstituted aromatic compounds specifically. The comparison of moiety in both inter- and intramolecular competition experiments vis a vis other established directed ortho metalation groups (CONR;Chapter 2. Following our concurrent study on Ni(0)-mediated cross coupling of aryl O-carbamates with Grignard reagents, the development of this process for aryl triflates was undertaken. The Ni(0)-catalyzed cross coupling of aryl triflates was undertaken. the Ni(0)-catalyzed cross coupling of aryl triflates with organozinc reagents was also developed. These triflate coupling processes were compared to the previously established Suzuki-Miyaura Reaction employing aryl triflates having various substituents on the aryl ring. The connection to directed ortho metalation was also employed to prepare the various organometallic reagents required. These competition experiments demonstrate the usefulness of the various methods, highlighting situations when one coupling variant proceeds better than the others.;Chapter 3. Studies were undertaken into the total synthesis of sterigmatocystin, a naturally occurring mycotoxin. A model study demonstrates our approach, which composed of initial diaryl ether formation followed by anionic-Friedel-Crafts equivalent cyclization to the xanthone. The required pentacyclic ring system was ultimately constructed via 5-exo-trig aryl radical cyclization. The investigation into the total synthesis of the mycotoxin proved unfruitful as the preparation of the required oxygenated xanthone was unsuccessful. A new approach is presented.