General strategy for stereoselective synthesis of 1-substituted exo,endo-2,6-diaryl-3,7-dioxabicyclo[3.3.0]octanes: total synthesis of (+/-)-gmelinol

[reaction: see text] A general strategy for stereoselective synthesis of 1-substituted exo,endo-2,6-diaryl-3,7-dioxabicyclo[3.3.0]octanes including (+/-)-gmelinol from (2,3-trans)-(4,5-cis)-alpha-aroylparaconic esters, which are readily obtained from the reaction of vicinal dianions derived from alpha-aroylsuccinic esters with aromatic aldehydes, is described. The synthetic sequence involves alpha-methylation or alpha-hydroxylation, reduction, bislactonization, and reduction followed by furofuran formation.     

Aigialomycins and related polyketide metabolites from the mangrove fungus Aigialus parvus BCC 5311

Reinvestigation of the secondary metabolites from the marine mangrove fungus Aigialus parvus BCC 5311 led to the isolation of six new nonaketide metabolites, aigialomycins F (4) and G (5a/5b), 7′,8′-dihydroaigialospirol (7), 4′-deoxy-7′,8′-dihydroaigialospirol (8), and rearranged macrolides 9 and 10, along with six previously described compounds, hypothemycin (1), aigialomycins A (2) and B (3), aigialospirol (6), 4-O-demethylhypothemycin (11), and aigialone (12). The structures of the new compounds were elucidated by analyses of the NMR spectroscopic and mass spectrometry data in combination with chemical means.     

Alpha-arylsulfanyl-alpha-fluoro carbenoids: their novel chemistry and synthetic applications

The bromine-magnesium exchange reactions of arylthiobromodifluoromethanes with Grignard reagents have been studied. Upon trapping with electrophiles, alkyl aryl sulfides and ketenedithioacetals are obtained. The reaction is proposed to occur via novel alpha-arylsulfanyl-alpha-fluoro carbenoids. The first examples of arylthiomethane multipole synthons are also reported. [reaction: see text]     

Unique diketopiperazine dimers from the insect pathogenic fungus Verticillium hemipterigenum BCC 1449

[structure: see text]. Vertihemiptellides A (1) and B (2), unique diketopiperazine dimers, were isolated from the insect pathogenic fungus Verticillium hemipterigenum BCC 1449. Structures of these compounds were elucidated by NMR and mass spectral analysis, and the stereochemistry of 1 was determined by X-ray crystallography. The absolute stereochemistry of bisdethiodi(methylthio)-1-demethylhyalodendrin (3), previously isolated from the same fungus, was revised to the (3R,6R) configuration.     

(Azido‐κN)bis­(di‐2‐pyridylamine)­copper(II) hexa­fluoro­phosphate and (azido‐κN)bis­(di‐2‐pyridylamine)­copper(II) chloride tetra­hydrate

The two new title complexes, [Cu(N₃)(dpyam)₂]PF₆ (dpyam is di‐2‐pyridylamine, C₁₀H₁₁N₃), (I), and [Cu(N₃)(dpyam)₂]Cl·4H₂O, (II), respectively, have been characterized by single‐crystal X‐ray diffraction. Both complexes display a distorted square‐pyramidal geometry. Each Cu atom is coordinated in the basal plane by three dpyam N atoms and one azide N atom in equatorial positions, and by another N atom from the dpyam group in the apical position. In complex (I), the one‐dimensional supra­molecular architecture is assembled via hydrogen‐bonding inter­actions between the amine N atom and terminal azide N atoms and the F atoms of the PF₆⁻ anion. For complex (II), hydrogen‐bonding inter­actions between the amine N atom, the Cl⁻ anion and water O atoms result in a two‐dimensional lattice.     

Terpenoids with potent antimycobacterial activity against Mycobacterium tuberculosis from Trigonostemon reidioides roots

Phytochemical investigation of Trigonostemon reidioides roots led to the isolation of fourteen compounds. These included six new diterpenoids, trigonoreidons A?F (1?6), together with eight known diterpenoids 7?14. The structures of the new compounds were elucidated by spectroscopic techniques and the absolute configuration at the asymmetric carbon was determined by the modified Mosher's method. The structure of trigonoreidon B (2) was confirmed by X-ray crystallographic analysis. The known compounds were identified by comparison of the spectroscopic and physical data with those of reported values. The isolated compounds were evaluated for antimycobacterial activity against Mycobacterium tuberculosis. Among the compounds that exhibited antimycobacterial activity, the diterpenoids rediocide C (12) and rediocide G (14) were the most active compounds, with the MIC value of 3.84 μM.     

A novel 8,9-seco-rhamnofolane and a new rhamnofolane endoperoxide from Jatropha integerrima roots

Integerrimene, a possible biogenetic precusor of the rhamnofolane diterpenes and a new rhamnofolane endoperoxide 2-epicaniojane together with caniojane and 1,11-bisepicaniojane were isolated from J. integerrima roots. Their structures were elucidated by spectroscopic methods. The X-ray structure of 2-epicaniojane is also presented.     

Lanostane triterpenoids from the edible mushroom Astraeus asiaticus

Seven new lanostane triterpenoids, astraeusins M–Q (1–5), 26-epi-artabotryol C1 (6), and 26-epi-astrasiaone (7), together with seventeen known compounds (8–24), were isolated from the food mushroom Astraeus asiaticus. The C-26 configuration of artabotriol C1 and astrasiaone, originally reported as 26R (6 and 7, respectively), was revised to be 26S (16 and 17, respectively). Astraeusin M (1) exhibited antimalarial activity against Plasmodium falciparum K1 with an IC₅₀ value of 3.0 μg/mL.