Abstract:

Caulibugulones (Figure 1) are marine isoquinoline alkaloids with anticancer activity isolated from briozoan Caulibugula intermis. Among caulibugulones A-D, compound B is the most active against CDC25 phosphatases. There are only two syntheses of this class of compounds and both of them were done at the same year of isolation. Both strategies use the oxidation of a preexistent isoquinoline nucleus as the key-step, and a sequence of amination/ oxidation/halogenation reactions to achieve these compounds. In our work we describe the synthesis of caulibugulone B using Pomeranz-Fritsch cyclization to build the isoquinoline nucleus and a oxidative ether cleavage of the alkoxy groups to give the desired compound.