- Synthesis of S-(+)-methoprene
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An optically active juvenile hormone analogue, S-(+)-methoprene (1), is synthesized in six steps from technical grade S-(+)-3,7-dimethyl-1,6-octadiene (''(+)-dihydromyrcene'', e.e. ca. 50percent) by a novel procedure which begins with selective hydroalumination-oxidation to give S-(-)-citronellol.This alcohol is oxidized to give S-(-)-citronellal which on reaction with allylmagnesium chloride affords 6S,10-dimethyl-1,9-undecadien-4R/S-ol (5).Smidt-Moiseev oxygenation of 5 followed by dehydration leads to 6S,10-dimethyl-3E,9-undecadien-2-one.The latter on treatment with isopropoxyethynylmagnesium bromide is transformed into isopropyl 3,7S,11-trimethyl-2E/Z,4E,10-dodecatrienoate which upon Brown solvomercuration-reduction in MeOH gives 1 in 14percent overall yield.
- Odinokov, V. N.,Ishmuratov, G. Yu.,Kharisov, R. Ya.,Serebryakov, E. P.,Tolstikov, G. A.
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- An expedient total synthesis of (±)-caparratriene
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(±)-Caparratriene has been synthesized by two succinct routes. The first relies on two Wittig reactions and produces (±)-caparratriene and its 2Z isomer as an inseparable 2:1 mixture. The second more efficient synthesis produces only the naturally occurring 2E isomer and proceeds in 36% overall yield. The key step in this short synthesis is the Suzuki coupling of E-2- bromo-2-butene with the E-vinyl borane derived from 4,8-dimethyl-7-nonen-1- yne.
- Vyvyan, James R.,Peterson, Emily A.,Stephan, Mari L.
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- Selective Synthesis of Unsymmetrical Aliphatic Acyloins through Oxidation of Iridium Enolates
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The first method to access unsymmetrical aliphatic acyloins is presented. The method relies on a fast 1,3-hydride shift mediated by an IrIII complex in allylic alcohols followed by oxidation with TEMPO+. The direct conversion of allylic alcohols into acyloins is achieved in a one-pot procedure. Further functionalization of the Cα′ of the α-amino-oxylated ketone products gives access to highly functionalized unsymmetrical aliphatic ketones, which further highlights the utility of this transformation.
- Sanz-Marco, Amparo,Martinez-Erro, Samuel,Martín-Matute, Belén
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supporting information
p. 11564 - 11567
(2018/07/31)
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- 2,2-Diiododimedone: A mild electrophilic iodinating agent for the selective synthesis of α-iodoketones from allylic alcohols
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2,2-Diiodo-5,5-dimethylcyclohexane-1,3-dione is reported as a new electrophilic iodinating agent that selectively iodinates electron-rich aromatics. In contrast to other common electrophilic iodinating reagents, its mild nature allows it to be used for the selective synthesis of α-iodinated carbonyl compounds from allylic alcohols through a 1,3-hydrogen shift/iodination process catalyzed by iridium(iii) complexes.
- Martinez-Erro, Samuel,Bermejo Gómez, Antonio,Vázquez-Romero, Ana,Erbing, Elis,Martín-Matute, Belén
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supporting information
p. 9842 - 9845
(2017/09/11)
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- Photochemical transformations of terpenoids in the presence of cyclodextrins
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The effect of complexation of terpene compounds with cyclodextrins on photolysis depends on the type of cyclodextrin and on the structure of the initial substrates. In some cases, only a change in the reaction rate is observed; in other cases, the complexation results in allylic rearrangements, hydride and acyl shifts, and cyclization with the formation of four-, five-, and six-membered cycles, whereas only cis-trans isomerization reactions are observed in the absence of complexation.
- Luzina,Tatarova,Korchagina,Salakhutdinov,Barkhash
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p. 183 - 193
(2007/10/03)
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- Nickel- and Palladium-Catalyzed Aldol-Type Condensation by Enol Esters
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PdCl2(PhCN)2-SnCl2, bis(1,5-cyclooctadiene)nickel(0) /PPh3-Zn, NiBr2(PPh3)2-Zn, or Pd-(OAc)2/PPh3-Zn catalytic systems induced aldol-type condensation of isopropenyl acetate with aldehydes to produce 4-substituted (E)-3-buten-2-ones.PdCl2(PhCN)2-SnCl2 was utilized in the aldol-type reaction with any arenecarbaldehyde, bearing either an electron-donating group or an electron-withdrawing group, at 50 deg C in acetonitrile.Catalytic systems using zinc, in particular Ni(cod)2/PPh3-Zn, exhibited some high chemoselectivities at 60 deg C in dioxane: (1) an aldehyde only reacted in the presence of an internal ester or ketone, (2) olefinic aldehydes only reacted in the presence of saturated aliphatic aldehydes, (3) reactivity in the condensation with substituted benzaldehydes is the inverse of that in usual nucleophilic addition to carbonyl compound, and (4) 2-methoxybenzaldehyde only reacted in the presence of 4-methoxybenzaldehyde.Using PdCl2(PhCN)2-SnCl2, Ni(cod)2/PPh3-Zn, or Pd(OAc)2/PPh3-Zn, cyclic enol ester, namely 5-methyl-2(3H)-furanone also caused aldol-type reaction with carbonyl compounds.The reaction with Ni(cod)2/PPh3-Zn or Pd(OAc)2/PPh3-Zn at 60 deg C in dioxane selectively produced 5-substituted 4-acetyl-2(5H)-furanones via dehydrogenation of γ-substituted β-acetyl-γ-butyrolactones.
- Masuyama, Yoshiro,Sakai, Tatsuya,Kato, Takeshi,Kurusu, Yasuhiko
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p. 2265 - 2272
(2007/10/02)
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- SYNTHESIS WITH MANGANIC SALTS; PART III: SYNTHESIS OF 1,4-DIKETONES THROUGH MANGANIC ACETATE-MEDIATED ADDITION OF KETONE TO ISOPENTENYL SULFONES. ACETOXYLATION OF Β,Γ-UNSATURATED KETONES BY MANGANOUS AND CUPRIC ACETATES
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Conditions have been found to selectively add ketones to isopentenyl sulfones.The major product, a ketone bearing a methylene group at the γ position, gave upon ozonolysis the corresponding 1,4-diketone.The usefulness of the overall process was illustrated by the efficient syntheses of jasmone and of one half of pyrenophorine.The γ-acetoxy conjugated enones that invariably formed during these additions resulted from the oxidation of an isomeric β,γ-unsaturated ketone by manganous and cupric acetates.Such an acetoxylation has been used to prepare 6β-acetoxy-cholestenone from cholesterol and also to prepare chrysanthemic acid.
- Breuilles, Pascal,Uguen, Daniel
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p. 705 - 720
(2007/10/02)
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