Biomimetic synthetic studies on meroterpenoids from the marine sponge Aka coralliphaga: Divergent total syntheses of siphonodictyal B, liphagal and corallidictyals A–D

Total Synthesis of (±)-Liphagal via Organic-Redox-Driven Palladium-Catalyzed Hydroxybenzofuran Formation

“…Because of its pronounced biological property, liphagal ( 1 ) has gained considerable attention from medicinal and synthetic chemists . In this context, successful efforts have been made independently by the groups of Andersen, , Mehta, George, Alvarez-Manzaneda, Kumar, Stoltz, Katoh, Ferreira, and Wu to chemically synthesize this natural product. In addition, Winne and Zhu have reported the synthesis of C5- epi -liphagal and C8- epi -liphagal, respectively.…”

Concise and Scalable Total Syntheses of Lamellarin Z and other Natural Lamellarins

“…The ethyl ester (7) was then elaborated to the phenyl esters (10 a,b) through a 2-step synthetic manoeuvre involving hydrolysis followed by EDC.HCl mediated coupling of the resultant pyrrole-2-carboxylic acid (8) with phenol 9 a,b. [16,17] After having access to 10 a,b we then executed the key Pd-mediated CDC reaction in presence of Cu (OAc) 2 as cooxidant to establish two CÀ C bonds in a consecutive manner between the central pyrrole core and the appended phenyl rings in the ester functionality as well as the phenyl ring of phenethyl substitution on the pyrrole-N-atom, to arrive at the pentacyclic lactones (11 a,b) in moderate yields. [10,15] Subsequently, exhaustive deisopropylation of the isopropyl ethers present on the aryl rings using BCl 3 smoothly delivered the target MPAs, lamellarin S and lamellarin Z in excellent yields.…”

Synthesis of Cyclosiphonodictyol A and Its Bis(sulfato)

“…Marine organisms are an important source of natural products, which have aroused great interest because of their structural variety and the wide range of biological activities that many of them exhibit. One such organism is the tropical marine sponge Aka coralliphagum (or Siphonodictyon coralliphagum) because of the considerable number of bioactive metabolites, usually with a sesquiterpene hydroquinone structure, that have been isolated from it, such as liphagal and corallidictyals A–D …”