Part~I. Consecutive use of two reactions of alkyne - dicobalt hexacarbanyl complexes in the total synthesis of (+)-epoxydictymene. Part~II. Studies directed toward the synthesis of the diazonamide marine natural products using benzofuran epoxidation-re

The diterpene (+)-epoxydictymene has been synthesized in 20 steps using the asymmetry of (R)-pulegone and several substrate-controlled diastereoselective reactions to prepare the natural product in its natural configuration. Three of epoxydictymene's four rings were assembled with two consecutive intramolecular reactions involving dicobalt hexacarbonyl complexes of alkynes: a Lewis acid-promoted Nicholas reaction and a Pauson-Khand reaction. The construction of the strained trans-3-oxabicyclo ºlbrack3.3.0) octane ring system of the natural product presented a significant challenge. To this end, several radical and anionic cyclizations were studied, the latter leading to (+)-epoxydictymene.*.;The left-hand macrocycle of the diazonamide class of natural products (2 and 3) has been prepared using an epoxidation-rearrangement of a benzofuran-containing macrocycle (4). Studies demonstrating an expedient strategy to the right-hand macrocycle have shown that DDQ-promoted oxidative cyclization of tryptophan amides (5) efficiently constructed the oxazole-oxazole-indole systems (6) shown below.* ftn*Please refer to the dissertation for diagrams.