Synthesis of Tuckolide, a New Cholesterol Biosynthesis Inhibitor

The Chemistry and Pharmacology of Fungal Genus Periconia: A Review

Periconia is filamentous fungi belonging to the Periconiaceae family, and over the last 50 years, the genus has shown interest in natural product exploration for pharmacological purposes. Therefore, this study aims to analyze the different species of Periconia containing natural products such as terpenoids, polyketides, cytochalasan, macrosphelides, cyclopentenes, aromatic compounds, and carbohydrates carbasugar derivates. The isolated compound of this kind, which was reported in 1969, consisted of polyketide derivatives and their structures and was determined by chemical reaction and spectroscopic methods. After some years, 77 compounds isolated from endophytic fungus Periconia were associated with eight plant species, 28 compounds from sea hare Aplysia kurodai, and ten from endolichenic fungi Parmelia sp. The potent pharmacological agents from this genus are periconicin A, which acts as an antimicrobial, pericochlorosin B as an anti-human immunodeficiency virus (HIV), peribysin D, and pericosine A as cytotoxic agents, and periconianone A as an anti-inflammatory agent. Furthermore, information about taxol and piperine from Periconia producing species was also provided. Therefore, this study supports discovering new drugs produced by the Periconia species and compares them for future drug development.

Stagonolides J and K and Stagochromene A, Two New Natural Substituted Nonenolides and a New Disubstituted Chromene-4,5-dione Isolated from Stagonospora cirsii S-47 Proposed for the Biocontrol of Sonchus arvensis

Two new natural 10-membered macrolides (1, 2) and one chromene-4,5-dione derivative (3), named stagonolides J and K and stagochromene A, respectively, were isolated from the phytopathogenic fungus Stagonospora cirsii S-47, together with two known compounds, stagonolide A (4) and herbarumin I (5). Stagonolides J and K and stagochromene A were characterized as (5E,7R*,8S*,9R*)-7,8-dihydroxy-9-propyl-5-nonen-9-olide, (5E,7R,9S)-7-hydroxy-9-propyl-5-nonen-9-olide, and (2R*,3R*)-3-hydroxy-2-propyltetrahydro-2H-chromene-4,5(3H,4aH)-dione, respectively, by spectroscopic (mostly by NMR and ESIMS) data. Compounds 1-5 showed different rates of phytotoxic activity on punctured leaf discs of Sonchus arvensis. The antimicrobial, cytotoxic, and antiprotozoal activity of isolated compounds was also evaluated. Based on our data, stagonolide K and herbarumin I can be proposed as a potential scaffold for the development of a new natural herbicide and estimated as possible selection/quality markers of a bioherbicide based on S. cirsii, while stagonolide A can be considered as a mycotoxin.

A highly efficient macrolactonization method via ethoxyvinyl ester

We present the highly efficient reaction procedure of the macrolactonization method via ethoxyvinyl esters (EVEs). The following procedure was performed: 1) The EVE was prepared from hydroxycarboxylic acid and ethoxyacetylene in the presence of the Ru catalyst [RuCl(2)(p-cymene)](2) in acetone; 2) after filtration of the Ru catalyst through a short-neutral SiO(2) pad and evaporation of acetone, the EVE formed was diluted in 1,2-dichloroethane (DCE) and the solution was slowly added by a syringe pump to the highly diluted DCE solution of pTsOH (10 mol %) at 80 degrees C. Various-sized lactones could be produced by the method described here. It is noteworthy that the method can give 9- to 14-membered macrolactones in good yields. This macrolactonization method via EVEs is useful for acid-/base-sensitive substrates. Furthermore, it was found that EVE formation was possible without loosing activity of the Ru catalyst even for the compounds with nucleophilic amine functions. The characteristic feature of the method was exemplified by the reaction of the compound 14 with many functional groups.

Nickel-Catalyzed Coupling Producing (2Z)-2,4-Alkadien-1-ols, Conversion to (E)-3-Alkene-1,2,5-triol Derivatives, and Synthesis of Decarestrictine D

The 3-alkene-1,2,5-triol structure is not only a major framework of biologically important molecules but also a new functional-group-rich unit for synthesis of polyols and sugars. A method furnishing such triol derivatives 8 was developed and successfully applied to synthesis of decarestrictine D (18). First, coupling reaction of the unprotected alcohols 2 with borates 4 was investigated to produce the dienyl alcohols 6 with NiCl2(dppf) in Et2O/THF (5:1) at room temperature. The hydroxyl-group-directed epoxidation of 6 followed by palladium-catalyzed reaction with AcOH (Scheme 1) furnished 3-alkene-1,2,5-triol derivatives 8. Since each step proceeded with high stereo- and regioselectivities, the stereochemistry of 8 has been correlated with the olefin geometry of 6. With the above transformation in mind, synthesis of the full carbon skeleton of decarestrictine D (18) could be designed easily and was completed successfully. Furthermore, a new seco acid 19b with the MOM protective group for the three hydroxyl groups was found to afford macrolide 48 in a yield higher than those reported previously.

Stereoselective synthesis of decarestrictine D from a previously inaccessible (2Z,4E)-alkadienyl alcohol precursor

[reaction: see text] The core structure of decarestrictine D was constructed by stereoselective oxygenation of (2Z,4E)-alkadienyl alcohol, which could be synthesized by a nickel-catalyzed coupling reaction between the corresponding cis bromide and trans borate. Efficiency in macrocyclization of the seco acid with Yamaguchi reagent was found to be protective-group-dependent, and the best yield of 40% was obtained with the seco acid with tri-MOM protective groups.

Asymmetric synthesis of A-240610.0 via a new atropselective approach for axially chiral biaryls with chirality transfer

A new approach for atropselective preparation of axially chiral biaryl was developed. This process proceeded through a chirality transfer from a stereogenic center of a secondary alcohol to the stereogenic axis via regioselective intramolecular silyl group migration. This methodology allowed for the preparation of a single atropisomer 2 in good yield (85%) with high diastereoselectivity (99:1), which subsequently led to the successful development of an efficient asymmetric synthesis of A-240610.0, 1.

Synthesis and biological testings as inhibitors of HMGCoA reductase of the seco-acid of tuckolide and its C-7 epimer

The seco-acid of the natural macrolactone, tuckolide (decarestrictin D) and the C-7 epimer have been prepared in enantiomerically pure form from D-gluconolactone and poly(3-hydroxy butyric acid). The key steps are Horner Emmons olefination and stereoselective reduction of the resulting enone to provide both epimers at C-7. None of the seco-acids inhibit microsomal HMGCoA reductase of pea or rat liver. It may be concluded that the cholesterol biosynthesis inhibiting effect of tuckolide is unlikely to proceed via HMGCoA reductase inhibition.

The synthesis and in vitro activity of some delta 7,9(11)-lanostadienes

The synthesis of delta 7,9(11)-lanostadiene derivatives functionalized at C(32) starting from 3 beta-acetoxy-7 alpha,32-epoxylanostan-11-one has been presented. The delta 7,9(11) moiety was efficiently introduced in three steps in 71% yield by the regioselective abstraction of allylic 8 beta hydrogen. The formyl group of the key intermediate, 3 beta-benzoyloxylanosta-7,9(11)-dien-32-al, has been stereoselectively alkylated into (32S) derivative, whereas its oxidation unexpectedly afforded 3 beta-benzoyloxy-7-oxolanost-8-ene-32,11 alpha-lactone and not the corresponding acid. delta 7,9(11)-lanostadienes possessing HC(32)=O, C(32) [symbol: see text] N, HC(32S)CH3OH, H2C(32)OH, as well as some 11-keto lanostenes, were tested in vitro against several purified cholesterogenic enzymes showing moderate activity, with most the active aldehyde 16 having IC50 = 86 microM.