18479-49-7Relevant articles and documents
Chemo-Enzymatic Oxidative Rearrangement of Tertiary Allylic Alcohols: Synthetic Application and Integration into a Cascade Process
Brenna, Elisabetta,Crotti, Michele,De Pieri, Matteo,Gatti, Francesco G.,Manenti, Gabriele,Monti, Daniela
supporting information, p. 3677 - 3686 (2018/06/04)
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.).
Preparation of C10-C30-alkenes by partial hydrogenation of alkynes over fixed-bed supported palladium catalysts
-
Example 6, (2008/06/13)
Alkenes are prepared by partial hydrogenation of alkynes in the liquid phase at from 20 to 250° C. and hydrogen partial pressures of from 0.3 to 200 bar over fixed-bed supported palladium catalysts which are obtainable by heating the support material in the air, cooling, applying a palladium compound and, if required, additionally other metal ions for doping purposes, molding and processing to give monolithic catalyst elements, by a process in whichA) alkynes of 10 to 30 carbon atoms are used as starting compounds,B) the palladium compound and, if required, the other metal ions are applied to the support material by impregnation of the heated and cooled support material with a solution containing palladium salts and, if required, other metal ions and subsequent drying, andC) from 10 to 2000 ppm of carbon monoxide (CO) are added to the hydrogenation gas or a corresponding amount of CO is allowed to form in the liquid phase by slight decomposition of a compound which is added to the reaction mixture and eliminates CO under the reaction conditions.The process is particularly advantageous if the partial hydrogenation is carried out in a tube reactor by the trickle-bed or liquid phase procedure with product recycling at cross-sectional loadings of from 20 to 500 m3/m2*h. The process is particularly suitable for the preparation of 3,7,11,15-tetramethyl-1-hexadecen-3-ol (isophytol), 3,7,11-trimethyl-l-dodecen-3-ol (tetrahydronerolidol), 3,7,11-trimethyl-1,4-dodecadien-3-ol, 3,7,11-trimethyl-1,6-dodecadien-3-ol (dihydronerolidol), 3,7-dimethyloct-1,6-dien-3-ol or 3,7-dimethyloct-1-en-3-ol from the corresponding alkynes.
Process for the preparation of tocopherol derivatives and catalyst
-
, (2008/06/13)
A process is provided for the preparation of an α-tocopherol derivatives which are useful as antisterile vitamins, hypolipidemics, blood flow increasing agents, anti-cytosenility agents, antioxidants and the like. Catalysts are also provided. The α-tocopherol derivatives are represented by the following formula (VII): STR1 wherein n stands for 0 or an integer of from 1 to 5. The derivatives can be industrially prepared by employing as catalyst a metal ion-exchanged montmorillonite, metal ion-exchanged bentonite or metal ion-exchanged saponite which is substituted with one metal ion selected from the group consisting of scandium, yttrium, lanthanide element, aluminium, iron, tin, copper, titanium, zinc, nickel, gallium or zirconium.
