13326-69-7

The first total synthesis of bussealin E, a natural product with a unique cycloheptadibenzofuran scaffold, is reported. A strategy inspired by a proposed biosynthesis was employed whereby a diphenylpropane derivative underwent an oxidative phenolic coupling to forge the tetracyclic ring system. The synthesis of the diphenylpropane featured a key sp2-sp3 Hiyama coupling between a vinyldisiloxane and a benzylic bromide.

A mild and efficient method for the vanadium-catalyzed intramolecular coupling of tethered free phenols is described. The corresponding phenol-dienone products are prepared directly in good yields with low catalyst loadings. Electronically diverse tethered phenol precursors are well tolerated, and the catalytic method was effectively applied as the key step in syntheses of three natural products and a synthetically useful morphinan alkaloid precursor.

The biosynthesis of thebaine is based on the regioselective, intramolecular, oxidative coupling of (R)-reticuline. For decades, chemists have sought to mimic this coupling by using stoichiometric oxidants. However, all approaches to date have suffered from low yields or the formation of undesired regioisomers. Electrochemistry would represent a sustainable alternative in this respect but all attempts to accomplish an electrochemical synthesis of thebaine have failed so far. Herein, a regio- and diastereoselective anodic coupling of 3′,4′,5′-trioxygenated laudanosine derivatives is presented, which finally enables electrochemical access to (?)-thebaine.

The invention relates to a chalcone derivative, a preparing method, a pharmaceutical composition and application, provides a compound with the general formula I, and pharmaceutically-acceptable salt or solvate or polymorphic substances or metabolites or prodrugs of the compound, and further provides a preparing method of the compound of the structure shown in the general formula I, a pharmaceutical composition including the substance, and application of the substance in preparing medicine for treating or preventing inflammation. The general formula I is shown in the description, wherein R1, R2, R3, R4, R5, R6, R7, R8 and R9 are H, substituted or unsubstituted C1-C4 alkyl, hydroxyl, alkoxy, amino, halogen, C1-C4 substituted acylamino and C1-C4 acyl; R11 and R12 are substituted or unsubstituted C1-C4 alkyl.

A convenient synthetic pathway enabling D-glucal and D-galactal pinacol boronates to be prepared in good isolated yields was achieved. Both pinacol boronates were tested in a series of cross-coupling reactions under Suzuki-Miyaura cross-coupling conditions to obtain the corresponding aryl, heteroaryl, and alkenyl derivatives in high isolated yields. This methodology was applied to the formal synthesis of the glucopyranoside moiety of papulacandin D and the first total synthesis of bergenin. Building blocks with boron: A convenient synthetic route to D-glucal and D-galactal pinacol boronates was developed, and the boronates were used in cross-coupling reactions to generate the corresponding aryl, heteroaryl, and alkenyl derivatives in high yields (see scheme). This methodology was applied to the formal synthesis of the glucopyranoside moiety of papulacandin D and the total synthesis of bergenin.

(±)-Megistophylline I (1), carrying a dienone residue in the acridone framework, was synthesized using the Claisen rearrangement to introduce a prenyl group as a key step.

Seven compounds (1-7) based on gallate were synthesized and characterized by elemental analysis, 1H NMR, and MS spectra. 2-(3,5-Dibenzyloxy-4- methoxy)phenyl-2-propanol (6) was a new compound. Methyl 3,5-dihydroxy-4- methoxybenzoate (3), methyl 3,5-dibenzyloxy-4-methoxybenzoate (4), 3,5-dibenzyloxy-4-methoxybenzyl alcohol (5), and compound 6 were structurally determined by single-crystal X-ray diffraction for the first time. Crystallography data for 3: space group P21212 1; a = 4.0750(8) A, b = 7.5880(15) A, c = 29.802(6) A; V = 921.5(3) A3 Z = 4. 4: space group P-1; a = 10.068(2) A b = 10.499(2) A, c = 11.388(2) A; α = 76.84(3)°, β= 66.79(3)°, γ = 64.10(3)°; V = 993.0(3) A3, Z = 2. 5: space group P-1; a = 8.1410(16) A, b = 8.7590(18) A, c = 12.879(3) A; α = 91.66(3)°, β= 94.69(3)°, γ = 91.73(3)°; V = 914.4(3) A3; Z = 2. 6: space group P21/c; a = 5.8100(12) A, b = 15.778(3) A, c = 23.237(5) A; β= 96.09(3)°; V = 2118.1(7) A3; Z = 4. All of the seven compounds were evaluated for the inhibition of growth of human hepatoma (HepG2) cells. Comparison with the positive-control 5-fluorouracil (IC50 51.6 μmol/L), 5 showed stronger cytotoxic activity with an IC50 around 15.3 μmol/L, while IC50 value of 3 was 90.3 μmol/L. The effect of slight structural variations in this series of compounds was found to cause a marked change in their activity against HepG2 cells.

(±)-Galanthamine (1) was synthesized in excellent yield by applying PIFA-mediated oxidative phenol coupling of N-(4-hydroxy)phenethyl-N-(3′, 4′,5′-trialkoxy)benzyl formamide (15b) as a key step. Because of the symmetrical characteristics of the pyrogallol moiety in the substrate (15b), the phenol coupling resulted in a sole coupling product except for volatile components from the oxidizing agent. On the basis of the successful results of the above strategy, (-)-galanthamine (1) was synthesized by employing a novel remote asymmetric induction, where conformation of the seven-membered ring in the product of the phenol coupling was restricted by forming a fused-chiral imidazolidinone ring with D-phenylalanine on the benzylic C-N bond of the tri-O-alkylated gallyl amino moiety. The conformational restriction and successive debenzylation of the protected hydroxyl groups on the pyrogallol ring caused diastereoselective cyclization to yield a cyclic ether having the desired stereochemistry for the synthesis of (-)-1.

The chiral 1,2,3,4-tetrahydroisoquinoline intermediates in the Price and Beyerman routes to morphine, (+)-(R)-1-(3-hydroxy-4-methoxybenzyl)-6-methoxy- 1,2,3,4-tetrahydroisoquinoline (6) and (+)-(R)-1-(3,5-dibenzyloxy-4- methoxybenzyl)-6-methoxy-1,2,3,4-tetrahydroisoquinoline (5), were prepared in high ee by ruthenium-catalyzed asymmetric transfer hydrogenation of the corresponding imine precursors (Noyori method). The yield of the key raw material in the Beyerman route, 3,5-dibenzyloxy-4-methoxyphenylacetric acid (1), starting from gallic acid methyl ester (7) was improved by a factor of 5 over previously described syntheses. Key steps in the new procedure are the selective formation of methyl 3,5-dihydroxy-4-methoxybenzoate (9) via the 3,5-diacetate and an improved benzylation of the hydroxyl groups in 9.

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The synthesis of (2RS,3SR)-1-(3,5-dihydroxy-4-methoxyphenyl)-(4-hydroxy-3,5-dimethoxyphenyl)2,3-dimethylbutan-1-one (26) is described.Diphenolic oxidative coupling of (26) did not produce a eupodienone-type product.An aryltetralin derivative was formed in

Junipegenin-A (1), a new isoflavone isolated from Juniperus macropoda has been synthesised in nine steps, starting from gallic acid.The key step is the oxidative rearrangement of the intermediate benzyloxychalkone (9) by thallium(III) nitrate to give acetal (10) followed by cyclisation to the corresponding isoflavone (1), identical (m.m.p., co-TLC and co-IR) with a natural sample.

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