Highly Efficient Total Synthesis of (+)‐Citreoviral

Abstract

Only eight steps were required for the total synthesis of (+)‐citreoviral (3) from chiral imide 1 in 18 % overall yield. The key steps included a highly anti‐selective aldol reaction, the stereoselective iodolactonization of a γ,δ‐unsaturated β‐hydroxyimide, and an intramolecular SN2 reaction of a tertiary alcohol to form intermediate 2.

Avertoxins A–D, Prenyl Asteltoxin Derivatives from Aspergillus versicolor Y10, an Endophytic Fungus of Huperzia serrata

“…The key HMBC correlations from OMe-17 to C-17, from H-4a to C-3, C-4, and C-5, from H-5a to C-4, C-5, C-6, and C-7, and from H-9 to C-8, C-10, and C-11 further collaborated those changes. Additionally, these NMR assignments are consistent with that for asteltoxin C. 6 It noteworthy that, in α-pyrones, the 13 C NMR chemical shifts of the α-positions (carbonyl) usually are more upfield than that of the γ-positions (hydroxy). 7 Compounds 2−5 were all obtained as light yellow powders and showed similar IR spectra to that of asteltoxin.…”

“…The extract obtained after the removal of solvents under vacuum was subjected to medium-pressure liquid chromatography (MPLC), column chromatography over Sephadex LH-20, and silica gel to yield compounds 1−5. The 1 H and 13 C NMR spectroscopic data of 1 are similar to those of asteltoxin. 5 However, the NMR assignments reported in literature should be exchanged between C-4a and C-5a, C-9 and C-14, and C-17 and C-19, respectively (Table S1).…”

“…Asteltoxin ( 1 ) and structurally related verrucosidins, citreoviridins, , and aurovertins − are a family of polyene α-pyrone-type polyketide mycotoxins . Recently, asteltoxins C and D, with antiproliferative activity against NIAS-SL64 cells, were reported .…”

4.07 Electrophilic Cyclization

“…The reaction could proceed smoothly to afford iodolactone in a 92% yield as a single isomer (Scheme 41). 46 An example of the preparation of 2,5-disubstituted THFs from isoxazoline-based substrate is shown in Scheme 42. 47 Dioxanes, trioxanes, or trioxepanes could be obtained from unsaturated hydroperoxyacetals and hydroperoxyketals via electrophilic cyclization in the presence of I 2 and base (Scheme 43).…”

Golden Opportunities in Stereoselective Catalysis: Optimization of Chirality Transfer and Catalyst Efficiency in the Gold-Catalyzed Cycloisomerization of α-Hydroxyallenes to 2,5-Dihydrofurans

“…Dihydrofurans or tetrahydrofurans bearing stereogenic centers in 2,5-positions represent a structural motif that is found in an abundance of natural products and pharmacologically active molecules. These include the (potentially antimalarial) diterpenoid kalihinol C, 2 the antifungal aminoacid furanomycin, 3 the fungal metabolite citreoviral, 4 and the cytotoxic goniothalesdiol 5 (Figure 1).…”