- Chemo-Enzymatic Oxidative Rearrangement of Tertiary Allylic Alcohols: Synthetic Application and Integration into a Cascade Process
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A chemo-enzymatic catalytic system, comprised of Bobbitt's salt and laccase from Trametes versicolor, allowed the [1,3]-oxidative rearrangement of endocyclic allylic tertiary alcohols into the corresponding enones under an Oxygen atmosphere in aqueous media. The yields were in most cases quantitative, especially for the cyclopent-2-en-1-ol or the cyclohex-2-en-1-ol substrates without an electron withdrawing group (EWG) on the side chain. Transpositions of macrocyclic alkenols or tertiary alcohols bearing an EWG on the side chain were instead carried out in acetonitrile by using an immobilized laccase preparation. Dehydro-Jasmone, dehydro-Hedione, dehydro-Muscone and other fragrance precursors were directly prepared with this procedure, while a synthetic route was developed to easily transform a cyclopentenone derivative into trans-Magnolione and dehydro-Magnolione. The rearrangement of exocyclic allylic alcohols was tested as well, and a dynamic kinetic resolution was observed: α,β-unsaturated ketones with (E)-configuration and a high diastereomeric excess were synthesized. Finally, the 2,2,6,6-tetramethyl-1-piperidinium tetrafluoroborate (TEMPO+BF4?)/laccase catalysed oxidative rearrangement was combined with the ene-reductase/alcohol dehydrogenase cascade process in a one-pot three-step synthesis of cis or trans 3-methylcyclohexan-1-ol, in both cases with a high optical purity. (Figure presented.).
- Brenna, Elisabetta,Crotti, Michele,De Pieri, Matteo,Gatti, Francesco G.,Manenti, Gabriele,Monti, Daniela
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supporting information
p. 3677 - 3686
(2018/06/04)
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- Chiral tetrafluorobenzobarrelenes as effective ligands for rhodium-catalyzed asymmetric 1,4-addition of arylboroxines to β,β-disubstituted α,β-unsaturated ketones
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(Chemical Equotion Present) Lock, Stock and Two Smoking Barrelenes: The rhodium-catalyzed 1,4-addition of readily available arylboronic acid anhydrides to simple β,β-disubstituted α,βunsaturated ketones creates quaternary carbon stereocenters with high enantiomeric excesses using a chiral tetrafluorobenzobarrelene ligand.
- Shintani, Ryo,Takeda, Momotaro,Nishimura, Takahiro,Hayashi, Tamio
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supporting information; experimental part
p. 3969 - 3971
(2010/09/03)
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- NIACIN RECEPTOR AGONISTS, COMPOSITIONS CONTAINING SUCH COMPOUNDS AND METHODS OF TREATMENT
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The present invention encompasses compounds of Formula (I): as well as pharmaceutically acceptable salts and hydrates thereof, that are useful for treating atherosclerosis, dyslipidemias and the like. Pharmaceutical compositions and methods of use are also included.
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Page/Page column 54
(2008/06/13)
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- Perfuming ingredients of the woody type
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The present invention relates to the use as perfuming ingredient of a decaline derivative of formula wherein R1 is a lower alkyl, the R2 to R5 are hydrogen atoms or lower alkyls and at least one dotted line is a double bon
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Page/Page column 5
(2008/06/13)
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- Perfuming ingredients of the woody type
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The present invention relates to the use as perfuming ingredient of a decaline derivative of formula wherein R1 is a lower alkyl, the R2 to R5 are hydrogen atoms or lower alkyls and at least one dotted line is a double bond, which is a useful perfuming ingredient of the woody or woody-citrus type.
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- Assessing the Substrate Selectivities and Enantioselectivities of Eight Novel Baeyer-Villiger Monooxygenases toward Alkyl-Substituted Cyclohexanones
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Genes encoding eight Baeyer-Villiger monooxygenases have recently been cloned from bacteria inhabiting a wastewater treatment plant. We have carried out a systematic investigation in which each newly cloned enzyme, as well as the cyclohexanone monooxygenase from Acinetobacter sp. NCIB 9871, was used to oxidize 15 different alkyl-substituted cyclohexanones. The panel of substrates included equal numbers of 2-, 3-, and 4-alkyl-substituted compounds to probe each enzyme's stereoselectivity toward a homologous series of synthetically important compounds. For all 4-alkyl-substituted cyclohexanones tested, enzymes were discovered that afforded each of the corresponding (S)-lactones in ≥98% ee. This was also true for the 2-alkyl-substituted cyclohexanones examined. The situation was more complex for 3-akyl-substituted cyclohexanones. In a few cases, single Baeyer-Villiger monooxygenases possessed both high regio- and enantioselectivities toward these compounds. More commonly, however, they showed only one type of selectivity. Nonetheless, enzymes with such properties might be useful as parts of a two-step bioprocess where an initial kinetic resolution is followed by a regioselective oxidation on the isolated, optically pure ketone.
- Kyte, Brian G.,Rouviere, Pierre,Cheng, Qiong,Stewart, Jon D.
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- Applications of the β-azidonation reaction to organic synthesis. α,β- Enones, conjugate addition, and γ-lactam annulation
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The β-azido functionalization reaction provides a mechanistically different enone synthesis that involves treatment of 2 with fluoride anion to effect desilylation and concomitant β-elimination to give 3. Table 1 lists a number of examples of the direct conversion of a TIPS enol ether into the corresponding α,β-enone via a β-azido TIPS enol ether. The β-azido group can be ionized with Me3Al or Me2AlCl and the intermediate enonium ion trapped by a variety of nucleophiles such as an allylstannane, electron-rich aromatics, TMS enol ethers, Et2AlCN, Me2AlCCR, Me4AlLi, and vinylaluminum reagents to give the products listed in Table 2. The diastereoselectivity of the reaction of a 4-substituted enonium ion with indole shows an unusual increase of selectivity with increasing temperature. Reduction of the azide 2 provides access to β-amino TIPS enol ethers 5, which, for example, can be converted into a cinnamide derivative and cyclized via a putative 'ene' process into a γ-lactam.
- Magnus, Philip
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p. 12486 - 12499
(2007/10/03)
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- Intramolecular Additions of Allylsilanes to Conjugated Dienones. The Synthesis of Three Perforanes
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Intramolecular addition of allylsilanes to 3-vinylcycloalkenones provides a powerful means of constructing functionalized 5-5, 5-7, 6-5, and 6-7 bicyclic ring systems.Our results reveal a divergence in reactivity, dependent on reaction catalyst and substr
- Majetich, George,Defauw, Jean,Ringold, Clay
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- A NEW PROCEDURE FOR DESULFONYLATION: PREPARATION OF β-SUBSTITUTED α,β-UNSATURATED KETONES AND ALDEHYDES
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The treatment of the tert-alkyl sulfones bearing carbonyl group at the β-position with 5 percent hydrochloric acid in THF at 30 - 65 deg C afforded β-substituted α,β-unsaturated ketones and aldehydes in excellent yields.
- Yoshida, Takashi,Saito, Shojiro
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p. 165 - 168
(2007/10/02)
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