Studies toward a total synthesis of (±)-subergorgic acid

• Main Author: Dragojlovic, Veljko
• Language: English
• Published: 2008
• Online Access: http://hdl.handle.net/2429/1233

This thesis describes synthetic studies directed towards the total synthesis of (±)-subergorgic acid (8) and the development of methodology for the conversion of cyclopentanones into cyclopentenones. In the synthetic studies directed towards the total synthesis of (±)-subergorgic acid (8), the known keto ketal 101 was converted into the enone 100. Copper(I)-catalyzed conjugate addition of the Grignard reagent 91 to the enone 100, followed by intramolecular alkylation of the intermediate enolate anion, provided the triquinane 99. Sequential deoxygenation of the keto function in 99 and oxidative cleavage of the double bond provided the ketone 103. The ketone 103 was converted into dienedione 98 via a four step sequence, involving Saegusa oxidation to give 156, deketalization of the ketal function and benzeneseleninic acid anhydride (BSA) mediated dehydrogenation of the intermediate 157. The dienedione 98 was alkylated to provide 107. Conversion of the enone 157 into the dienedione 98 required the development of new methodology for the conversion of cyclopentanones into the corresponding cyclopentenones. Reactions of di- and triqiunanes [sic] such as 133 and 157 with BSA provided the corresponding enones 250 and 98, respectively.