Total synthesis of novel Bisabolene derivatives from the marine sponge Myrmekioderma sp.

Abstract

Recently, some bisabolene derivatives were isolated from the marine sponge Myrmekioderma sp. These derivatives have shown lipid-reducing activity and offer exciting compounds for total synthesis. The goal of this project was the total synthesis of these derivatives, as many as possible. There are five derivatives in total and the basic-structure of all of them is similar. This makes it possible to synthesize the more complex structures from their simpler precursor. The first derivative that was synthesized is also the simplest one. Fries rearrangement played a key role in the synthesis of it. An attempt was made to synthesize the second derivative from the first derivative using the Wittig reaction as the key reaction, but that had never been used before in this kind of synthesis. Had this synthesis proven to be successful it would have opened up the possibility to synthesise the other three derivatives. From derivative 2, compound 3 can be synthesised in two steps, it should be possible to get a racemic mixture of compound 4 in one step, and the planned synthesis of compound 5 is three steps. A retrosynthetic analysis has been performed for all the structure and a suitable pathway to synthesize them has been found. After the synthesis the structures of these compounds were analyzed to confirm that the right products were obtained. All of the structures were analyzed using 1H-NMR, 13C-NMR, 2D NMR, and MS, and compared to known spectra of these compounds.