- Photocatalytic Upgrading of Lignin Oil to Diesel Precursors and Hydrogen
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Producing renewable biofuels from biomass is a promising way to meet future energy demand. Here, we demonstrated a lignin to diesel route via dimerization of the lignin oil followed by hydrodeoxygenation. The lignin oil undergoes C?C bond dehydrogenative coupling over Au/CdS photocatalyst under visible light irradiation, co-generating diesel precursors and hydrogen. The Au nanoparticles loaded on CdS can effectively restrain the recombination of photogenerated electrons and holes, thus improving the efficiency of the dimerization reaction. About 2.4 mmol gcatal?1 h?1 dimers and 1.6 mmol gcatal?1 h?1 H2 were generated over Au/CdS, which is about 12 and 6.5 times over CdS, respectively. The diesel precursors are finally converted into C16–C18 cycloalkanes or aromatics via hydrodeoxygenation reaction using Pd/C or porous CoMoS catalyst, respectively. The conversion of pine sawdust to diesel was performed to demonstrate the feasibility of the lignin-to-diesel route.
- Dou, Zhaolin,Wang, Min,Zhang, Zhe,Zhou, Hongru
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supporting information
p. 16399 - 16403
(2021/06/27)
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- Regioselective and Stereoselective Heck-Matsuda Arylations of Trisubstituted Allylic Alkenols and Their Silyl and Methyl Ether Derivatives to Access Two Contiguous Stereogenic Centers: Expanding the Redox-Relay Process and Application in the Total Synthesis of meso-Hexestrol
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Novel palladium-catalyzed redox-relay Heck arylation reactions of trisubstituted allylic alkenols were developed employing silyl and methyl ethers. The reactions proceeded under mild conditions in moderate to high yields in an excellent anti diastereoselectivity to form α,β-disubstituted methyl ketones containing two contiguous stereocenters. The new redox-relay arylations using silyl and methyl ethers of the starting alkenols demonstrate that the presence of a free hydroxyl group is not a sine qua non condition for an effective redox-relay process as previously thought. Deuterium-labeled alkenols 2-d-10a, 2-d-10b, and 2-d-10c permitted tracking the palladium-hydride reinsertion steps in the conversion of the starting free alcohols, silyl, and methyl ethers into the corresponding methyl ketone 3-d-11a, with >98% deuterium retention. Moreover, the synthetic potential of the method was demonstrated with a straightforward synthesis of the meso-hexestrol in 4 steps, in 41% overall yield from alkenol 10a.
- Frota, Carlise,Polo, Ellen Christine,Esteves, Henrique,Correia, Carlos Roque Duarte
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p. 2198 - 2209
(2018/02/23)
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- Cobalt-catalyzed arylzincation of alkynes
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Cobalt(II) bromide catalyzes arylzincation of alkynes with arylzinc iodide·lithium chloride complexes in acetonitrile. The scope of the arylzincation is wide enough to use unfunctionalized alkynes, such as 6-dodecyne, as well as arylacetylenes. The inherent functional group compatibility of arylzinc reagents allows preparation of various functionalized styrene derivatives. The reaction is applicable to the efficient and stereoselective synthesis of a synthetic estrogen and its derivative.
- Murakami, Kei,Yorimitsu, Hideki,Oshima, Koichiro
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experimental part
p. 2373 - 2375
(2009/12/01)
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- Tetrahydrofuran-mediated radical processes: Stereoselective synthesis of d,l-hexestrol
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The highly stereoselective synthesis of d,l-hexestrol (1), an inhibitor of microtubule assembly, is developed by using, as a key step, an intermolecular coupling of Co2(CO)6-complexed propargyl radicals. The latter are generated by novel complementary processes involving an interaction of tetrahydrofuran with Co2 (CO)6-complexed propargyl alcohols and cations. An isomerically pure d,l-μ-η2-[3,4-di(4-methoxyphenyl)-1, 5-hexadiyne]-bis-dicobalthexacarbonyl (d,l-6) is isolated in 69-91% yield with intermolecular coupling reactions exhibiting an excellent chemo-(0.5-7%) and d,l-diastereoselectivity (90-94%). The structure of d,l-6 is determined by X-ray diffraction. The subsequent steps include BBr3-induced demethylation of 4-methoxyaryl groups, demetalation with cerium(IV) ammonium nitrate, and hydrogenation of acetylenic termini affording d,l-hexestrol (1).
- Melikyan, Gagik G.,Sepanian, Steve,Riahi, Bobby,Villena, Ferdinand,Jerome, John,Ahrens, Brian,McClain, Randolph,Matchett, John,Scanlon, Stephanie,Abrenica, Edwin,Paulsen, Kevin,Hardcastle, Kenneth I.
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p. 324 - 330
(2007/10/03)
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- Estrogen receptor-β potency-selective ligands: Structure-activity relationship studies of diarylpropionitriles and their acetylene and polar analogues
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Through an effort to develop novel ligands that have subtype selectivity for the estrogen receptors alpha (ERα) and beta (ERβ), we have found that 2,3-bis(hydroxyphenyl)propionitrile (DPN) acts as an agonist on both ER subtypes, but has a 70-fold higher relative binding affinity and 170-fold higher relative potency in transcription assays with ERβ than with ERα. To investigate the ERβ affinity- and potency-selective character of this DPN further, we prepared a series of DPN analogues in which both the ligand core and the aromatic rings were modified by the repositioning of phenolic hydroxy groups and by the addition of alkyl substituents and nitrile groups. We also prepared other series of DPN analogues in which the nitrile functionality was replaced with acetylene groups or polar functions, to mimic the linear geometry or polarity of the nitrile, respectively. To varying degrees, all of the analogues show preferential binding affinity for ERβ (i.e., they are ERβ affinity-selective), and many, but not all of them, are also more potent in activating transcription through ERβ than through ERα (i.e., they are ERβ potency-selective). meso-2,3-Bis(4-hydroxyphenyl)succinonitrile and dl-2,3-bis(4-hydroxyphenyl)succinonitrile are among the highest ERβ affinity-selective ligands, and they have an ERβ potency selectivity that is equivalent to that of DPN. The acetylene analogues have higher binding affinities but somewhat lower selectivities than their nitrile counterparts. The polar analogues have lower affinities, and only the fluorinated polar analogues have substantial affinity selectivities. This study suggests that, in this series of ligands, the nitrile functionality is critical to ERβ selectivity because it provides the optimal combination of linear geometry and polarity. Furthermore, the addition of a second nitrile group β to the nitrile in DPN or the addition of a methyl substitutent at an ortho position on the β-aromatic ring increases the affinity and selectivity of these compounds for ERβ. These ERβ-selective compounds may prove to be valuable tools in understanding the differences in structure and biological function of ERα and ERβ.
- Meyers,Sun,Carlson,Marriner,Katzenellenbogen,Katzenellenbogen
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p. 4230 - 4251
(2007/10/03)
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