Novel chemistry of α-tosyloxy ketones:: Applications to the solution- and solid-phase synthesis of privileged heterocycle and enediyne libraries

New synthetic technologies for the preparation and elaboration of a-tosyloxy ketones in solution-and on solid-phase are described, Both olefins and ketones serve as precursors to these relatively stable chemical entities: olefins via a novel one-pot epoxidation, arylsuffonic acid displacement, and oxidation sequence, and ketones by direct exposure to arylsulfonic acids in the presence of diacetoxy iodobenzene. Reaction of these substrates with O-, S-, or N-centered nucleophiles leads to incorporation of the nucleophile with concomitant expulsion of the sulfonate, while exposure to bis-functional nucleophiles furnishes annulated heterocyclic systems. In addition, the reactions of carbon-centered nucleophiles with alpha-tosylyloxy ketones are also explored. The collated data for all these nucleophiles provide compelling evidence for the proposal that different reaction pathways are followed when a-tosyloxy ketones are engaged by "hard" versus "soft" nucleophiles. The accessibility and site-selectivity of the chemistry demonstrated herein offer the promise of an expanded use for this moiety in solid-phase library construction, in particular, and in the field of organic synthesis, in general.