Woo-Young Lee

Synthetic Studies on Jasmonoids (II)1: A New Synthesis Of Methyl dl-Jasmonate

Abstract Successive dialkylation of methyl acetoacetate with allylic functions 2 and 5, followed by oxidation, gave an α,β-unsaturated aldehyde 7. Intramolecular Michael addition of 7 to give a cyclopentanone 8, conversion to diester 9, and Krapcho decarbomethoxylation furnished methyl dl-jasmonate.

A TOTAL SYNTHESIS OF ISOSOLANONE

Abstract Nitroaldol reaction of acetone with nitromethane in the presence of base to give a nitroalcohol 3, followed by acetylation, and subsequent reduction of the resultant acetate 4 with NaBH4 gave 2-methyl-1-nitropropane 5. Michael reaction of 5 in base with acrylonitrile to give nitronitrile 6, and Nef conversion of the nitro group resulted in the corresponding ketonic nitrile 7. Wittig olefination of the ketonic nitrile with 3-methyl-2-butenyl triphenylphosphonium bromide 8 gave dienenitrile 9, which upon treatment with MeLi, followed by acidic work up, provided isosolanone 2.

Biotransformation of dehydroparadols byAspergillus niger

To prove uniqueness of allylic alcohol formation from α,β-unsaturated ketones by mammal enzymes, a metabolic pattern of dehydroparadols, non-pungent synthetic analogs of shogaol byAspergillus niger was examined. Two biotransformation products of a dehydroparadol, 1-(4-hydroxy-3-methoxyphenyl)-non-1-en-3-one were accumulated in the culture broth ofA. niger. They were characterized as 1-(4-hydroxy-3-methoxyphenyl)-non-1-en-9-ol-3-one and 1-(4-hydroxy-3-methoxyphenyl)-nonan-9-ol-3-one by UV, NMR and mass spectroscopic analyses. Accumulation of allylic alcohol metabolites was not observed.

Biscyclophanes. Part 2: Regioselectivity in the acid-catalysed cycloalkylation of benzylbenzylic alcohol (BBA)

o-Benzylbenzylic alcohols (o-BBAs), in which the terminal benzyl alcohol is substituted by repeating benzyl chains all in the ortho sense, have been found to have conspicuous regioselectivity in acid catalysed cycloalkylation, giving rise to various cyclophanes as intramolecular Friedel–Crafts alkylation products. The structure of the cyclisation products was largely dependent upon the size of the benzylic alcohols. Acidic treatment of 2-nuclear o-BBA 6 gave a [1.1]orthocyclophane 7 with a 6-membered ring, whereas 3-nuclear o-BBA 1 afforded [1.1.1]orthocyclophane 2 with a 9-membered ring in preference to a 6-membered-ring product. Higher homologues, such as 4- and 5-nuclear o-BBAs, gave rise to [1·4](1,2)(1,2)(1,2)(1,3)cyclophanes 14 and 25 with a 13-membered ring unit, respectively. Cyclophanes with a larger-than-1 3-membered ring have never been isolated as cycloalkylation products of o-BBA. Generalisations have been made about the priority of formation of cycles in the cycloalkylation of o-BBA in acid, to give a cycloalkylation rule, which involves the priority order of 13-membered ring > 9-membered ring > 6-membered ring. The regioselectivity was consistent with the acid-catalysed cycloalkylation of α,ω-benzylbenzylic diols, which yielded common-nuclear biscyclophanes. The sizes and structures of the biscyclophane products are also dependent upon the sizes and structures of the terminal benzylic diols.

A new synthesis of (±)-myodesmone

Abstract(±)-Myodesmone was synthesized, starting from 2-cyclopentenone. The key reaction involved α-dimethoxymethylation of 2-cyclopentenone and organocopper conjugate addition reaction.

Biscyclophanes. Part 1: synthesis of a common-nuclear bis[1.1.1 ]orthocyclophane. First member of a new family of cyclophanes

Synthesis of new orthocyclophane hosts has been investigated by the acid-catalysed intramolecular Friedel–Crafts cycloalkylation of terminal benzylbenzylic alcohols that bear repeating benzyl chains. Treatment of 2-(2-benzylbenzyl)benzyl alcohol 6 with concentrated sulfuric acid in acetic acid medium gave rise to a cyclisation product, [1.1.1]orthocyclophane 2. Similar cyclisation behaviour was observed under the same reaction conditions by the use of diterminal benzylbenzylic diols, which provided a common-nuclear bisorthocyclophane. Treatment of a solution of either the α,ω-benzylic diols 1,3-bis-{2-[2-(hydroxymethyl)benzyl]benzyl}benzene 16 in acetic acid or the 1,4-isomer 20 in acetic acid–dimethyl sulfoxide with concentrated sulfuric acid provided heptacyclo-[19.15.0.03,19.05,10.012,17.023,28.030,35]hexatriaconta-1 (21 ),2,5(10),6,8,12(17),13,15,19,23 (28), 24,26, 30(35),31,33- pentadecaene 3 which is the first member of a family of novel biscyclophanes.