Total syntheses of (+)-thyrsiferol, (+)-thyrsiferyl 23-acetate, and (+)-venustatriol

Stereochemistry of 2,2,5‐trisubstituted tetrahydrofuran ring‐containing natural products based on 1H NMR spectroscopy: some observations

“…It is of interest to note that when there was a cyclobutane ring and a THF ring in the side chain as in 10 (Fig. 7), there was accordance with the observations of Hashimoto et al [42] and a triplet observed for H-24.…”

“…Their relative stereochemistry was determined by NOESY cross-peak intensities, which have apparently been sufficient to determine cis versus trans configurations. [11] We will examine if the observations of Hashimoto et al [42] hold in various compounds containing a THF ring. Recently, we isolated ten malabaricane triterpenes from the oleoresin of Ailanthus malabarica.…”

“…Hashimoto et al observed that the 1 H NMR spectra of protons on THF rings of cis and trans isomers of squalene-derived polyethers showed specific splitting patterns and coupling constants. [42] We made some interesting observations while applying the findings of Hashimoto et al to some malabaricanes and other classes of compounds, which are discussed in the succeeding text.…”

(Schiff‐base)vanadium(V) Complex‐Catalyzed Oxidations of Substituted Bis(homoallylic) Alcohols − Stereoselective Synthesis of Functionalized Tetrahydrofurans

“…[2,16] This procedure has been successfully applied for the synthesis of tetrahydrofuran subunits of polyether-derived natural products such as lasalocid A, [17] ionomycin, [18] teurilene, [19] ferensimycin B, [20] glabrescol, [21] venustatriol, [22] or thyrsiferol. [23] Surprisingly, until now this method has not been further explored, either (i) by conducting a concise structure-selectivity survey or (ii) by application of auxiliaries other than exclusively diketonate ligands, in order to improve the reactivity and stereoselectivity of the active oxidant. Such achievements could have contributed to the development of reagents that were able to inhibit transformations which frequently interfere with selective tetrahydrofuran formation, for instance epoxidations of allylic π-bonds [24] or electron transfer and succeeding radical reactions.…”

Seaweeds as Source of New Bioactive Prototypes

“…This compound exhibited significant cytotoxic activity against cancer cells P-388, with CC 50 value of 0.6 µg/mL [104]. In order to obtain products with biological activity, synthesis of some halogenated triterpenes have been proposed, for example, the synthesis of Thyrsiferol (39) [105]. Using low concentrations of this product (3 µM), we observed 60% inhibition of Hypoxia-inducible factors-1 in T47D human breast cancer cells.…”