- Ti-direct, powerful, stereoselective aldol-type additions of esters and thioesters to carbonyl compounds: Application to the synthesis and evaluation of lactone analogs of jasmone perfumes
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An efficient TiCl4-Et3N or Bu3N-promoted aldol-type addition of phenyl and thiophenyl esters or thioaryl esters with aldehydes and ketones was performed (total 46 examples). The present method is advantageous from atom-economical and cost-effective viewpoints; good to excellent yields, moderate to good syn-selectivity, substrate variations, reagent availability, and simple procedures. Utilizing the present reaction as the key step, an efficient short synthesis of three lactone [2(5H)-furanone] analogs of jasmine perfumes was performed. Among them, the lactone analog of cis-jasmone had a unique perfume property (tabac). The Royal Society of Chemistry.
- Nagase, Ryohei,Matsumoto, Noriaki,Hosomi, Kohei,Higashi, Takahiro,Funakoshi, Syunsuke,Misaki, Tomonori,Tanabe, Yoo
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p. 151 - 159
(2008/03/28)
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- Biosynthesis of tetronasin: Part 6. Preparation of structural analogues of the diketide and triketide biosynthetic precursors to tetronasin
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The preparation of three analogues of the putative diketide biosynthetic precursor (2) and eight analogues of the putative triketide biosynthetic precursor (3) of the acyl tetronic acid ionophore tetronasin, as N-acetylcysteamine thioesters (4), (5), (6), (12), (13), (14), (15), (22), (23), (24) and (25) is described. Five examples are 19F-labelled; a new, enantiospecific method for the creation of a fluorinated quarternary α-centre is presented.
- Less, Simon L.,Handa, Sandeep,Millburn, Karen,Leadlay, Peter F.,Dutton, Christopher J.,Staunton, James
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p. 3515 - 3518
(2007/10/03)
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- Regio- and Stereoselective Ring Opening of ω-Alkenyllactones Using Organocopper Reagents
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New synthetic methods are described for the preparation of (E)-3, (E)-4, and (E)-5-alkenoic acids by the regio- and stereoselective ring opening of β, γ, and δ-lactones with unsaturated substituents at the ω-position using organocopper reagents such as halomagnesium diorganocuprates or Grignard reagents in the presence of copper(I) iodide.Both the organocopper reagents with primary, secondary, tertiary alkyl, and phenyl groups gave the corresponding carbon homologated alkenoic acids in good yields.Alkadienoic acids were also obtained in good yields by the reactions of ω-alkenyllactones with divinyl- and diallylcuprates.Utilizing the ring opening of β-isopropenyl-β-propiolactone, homoterpenoid carboxylic acids were easly obtained in good yields.The ring opening of β-(1-chlorovinyl)-β-propiolactone afforded 4-chloro-3-alkenoic acids which were easly transformed to 4-oxoalkanoic acids and 4-oxo-2-alkenoic acids.
- Kawashima, Masatoshi,Sato, Toshio,Fujisawa, Tamotsu
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p. 3255 - 3264
(2007/10/02)
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- NEW SYNTHETIC METHOD OF (Z)-4-ALKENOIC ACIDS USING RING-OPENING REACTION OF (Z)-4-HEXENOLIDE WITH ORGANOCOPPER REAGENT
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(Z)-4-Hexenolide reacted regioselectively with diorganocuprates to give (Z)-4-alkenoic acids in high yields.Synthetic utility was demonstrated by the convenient synthesis of cis-jasmone.
- Fujisawa, Tamotsu,Umezu, Kazuto,Kawashima, Masatoshi
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p. 1795 - 1798
(2007/10/02)
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- OXIDATION OF ALCOHOLS BY ELECTROCHEMICALLY REGENERATED NICKEL OXIDE HYDROXIDE. SELECTIVE OXIDATION OF HYDROXYSTEROIDS
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Primary alcohols, α,ω-diols and secondary alcohols are easily transformed into carboxylic acids, dicarboxylic acids or ketones, respectively, by heterogeneous oxidation with nickel oxide hydroxide electrochemically regenerated at a nickel hydroxyde electrode.The results are discussed in comparison to those of the nickel peroxide and chromic acid oxidation.The oxidation rate decreases with increasing steric hindrance of the alcohol, thus allowing the selective oxidation of the 3-position in hydroxysteroids.
- Kaulen, Johannes,Schaefer, Hans-J.
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p. 3299 - 3308
(2007/10/02)
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- SIMPLE METHODS FOR, THE SYNTHESIS OF (E)-4- AND (E)-5-ALKENOIC ACIDS BY THE SN2' TYPE REACTIONS OF γ-VINYL-γ-BUTYROLACTONE AND δ-VINYL-δ-VALEROLACTONE WITH ORGANOCOPPER REAGENTS
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γ-Vinyl-γ-butyrolactone and δ-vinyl-δ-valerolactone react regio- and stereoselectively with Grignard reagents in the presence of a copper(I) catalyst or with diorganocuprates to afford (E)-4- and (E)-5-alkenoic acids, respectively, in high yields.Synthetic utility of the former reaction is demonstrated in the simple synthesis of (4E,7Z)-4,7-tridecadienyl acetate.
- Fujisawa, Tamotsu,Sato, Toshio,Kawashima, Masatoshi,Naruse, Kouichi,Tamai, Kouichi
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p. 3583 - 3586
(2007/10/02)
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