Iodo–sesquiterpene hydroquinone and brominated indole alkaloids from the Thai sponge Smenospongia sp.

Anticancer agents from marine sponges

“…Many of the sterols Figure 9. Structure of aplysamine (14). Journal of Asian Natural Products Research 5 found in sponges are different from those of continental environments [20].…”

“…6 0 -Iodoaureol (12) (Figure 7) which possesses an iodo sesquiterpene hydroquinone was isolated from the Thai sponge Smenospongia sp. 6 0 -Iodoaureol (12) was moderately cytotoxic against MOLT-3 and HepG2 cells with the respective IC 50 values of 39.8 and 44.7 mM in vitro [14].…”

Convergent Assembly of the Tetracyclic Meroterpenoid (−)‐Cyclosmenospongine by a Non‐Biomimetic Polyene Cyclization

“…To the best of our knowledge,precursors that contain more complex substituents or heteroatoms at the central olefin unit have been unexplored (Figure 1b). [6,7] Our studies revealed that subtle modifications within the acyclicp recursor proved to be crucial for the successful cyclization, which generates three rings and sets three stereocenters in asingle transformation. [4] Herein we describe the first realization of anon-biomimetic cationic polyene cyclization and its application to the convergent assembly of the marine natural product (À)-cyclosmenospongine (1), [5] whose tetracyclic carbon framework is conserved among aw hole family of meroterpenoids with remarkable biological activities.…”

“…Since the double-bond geometry was inconsequential for the subsequent steps,cleavage of the silyl ether and iodination was carried out without further separation of the isomers to give iodide 8 in good yield on multigram scale.Initial attempts to establish agold(I)-catalyzed addition of p-methoxyphenol (6)t o7 were unsuccessful due to ac ompeting enyne cyclization. Thei ntermediate bromo enol ether, which is surprisingly stable to flash-column chromatography on silica gel, was then converted into 13 by dihydroxylation of the sterically less hindered olefin using freshly prepared AD-mix-a [K 2 OsO 4 ·2 H 2 O, (DHQ) 2 Phal, K 2 CO 3 ,K 3 Fe(CN) 6 ]a nd subsequent intramolecular displace-ment of the secondary alcohol via the corresponding mesylate.S ince low yields were encountered in aN egishi crosscoupling reaction between iodide 8 and enol ether 13,w e considered the B-alkyl Suzuki-Miyaura coupling reaction [11] as av iable alternative.U nder the optimized reaction conditions (5 mol %SPhos Pd G2, 5mol %SPhos,Cs 2 CO 3 ,THF, DMF,H 2 O, 40 8 8C), coupling of 11 with 13 proceeded efficiently to afford the cyclization precursor 5 in excellent yield (85 %, 5. [10] Extensive experimentation revealed that the reaction proceeded best in N,N-dimethylformamide (DMF;1.0 m) at 70 8 8C, employing excess phenol (10 equiv) and cesium carbonate as base (3 equiv).…”

Sterols from Thai Marine Sponge Petrosia (Strongylophora) sp. and Their Cytotoxicity

“…As part of our on-going search for biologically active metabolites from marine organisms [1,2,3], we have investigated a sponge species belonging to the genus Petrosia ( Strongylophora ) collected from the Similan Island, Thailand. Previously, various studies on the chemical constituents of Petrosia sp.…”