- 6-(1-Hydroxy-2,2-diphenylethyl)-4,4-diphenyl-2-cyclohexen-1-one
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The crystal structure of the title compound, C32H28O2, (I), confirms the erythro stereochemistry of the aldol adduct. In the crystal, (I) forms centrosymmetric O-H...O=C hydrogen-bonded dimers which in turn are connected by C-H...O and C-H...π interactions.
- Senthil Kumar,Nangia, Ashwini
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- Platinum-Catalyzed α,β-Desaturation of Cyclic Ketones through Direct Metal–Enolate Formation
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The development of a platinum-catalyzed desaturation of cyclic ketones to their conjugated α,β-unsaturated counterparts is reported in this full article. A unique diene-platinum complex was identified to be an efficient catalyst, which enables direct metal-enolate formation. The reaction operates under mild conditions without using strong bases or acids. Good to excellent yields can be achieved for diverse and complex scaffolds. A wide range of functional groups, including those sensitive to acids, bases/nucleophiles, or palladium species, are tolerated, which represents a distinct feature from other known desaturation methods. Mechanistically, this platinum catalysis exhibits a fast and reversible α-deprotonation followed by a rate-determining β-hydrogen elimination process, which is different from the prior Pd-catalyzed desaturation method. Promising preliminary enantioselective desaturation using a chiral-diene-platinum complex has also been obtained.
- Chen, Ming,Dong, Guangbin
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supporting information
p. 7956 - 7961
(2021/03/01)
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- COMPSTATIN ANALOGS WITH IMPROVED POTENCY AND PHARMACOKINETIC PROPERTIES
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Compounds comprising peptides capable of binding C3 protein and inhibiting complement activation are disclosed. The compounds include a modified compstatin peptide or analog thereof, comprising an added N-terminal component that improves (1) the binding a
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Page/Page column 29-30
(2015/11/11)
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- Conformational, concomitant polymorphs of 4,4-diphenyl-2,5- cyclohexadienone: Conformation and lattice energy compensation in the kinetic and thermodynamic forms
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4,4-Diphenyl-2,5-cyclohexadienone (1) crystallized as four conformational polymorphs and a record number of 19 crystallographically independent molecules have been characterized by low-temperature X-ray diffraction: form A (P2 1, Z′=1), form B (P1, Z′ = 4), form C (P1, Z′=12), and form D (Phca, Z′ = 2). We have now confirmed by variable-temperature powder X-ray diffraction that form A is the thermodynamic polymorph and B is the kinetic form of the enantiotropic system A-D. Differences in the packing of the molecules in these polymorphs result from different acidic C-H donors approaching the C=O acceptor in C-H...O chains and in synthons I-III, depending on the molecular con formation. The strength of the C-H...O interaction in a particular structure correlates with the number of symmetry-independent conformations (Z′) in that polymorph, that is, a short C-H...O interaction leads to a high Z′ value. Molecular conformation (Econf) and lattice energy (Ulatt) contributions compensate each other in crystal structures A, B, and D resulting in very similar total energies: Etotal of the stable form A = 1.22 kcal mol1, the metastable form B = 1.49 kcal mol-3, and form D = 1.98 kcal mol-1. Disappeared polymorph C is postulated as a high-Z′ high-energy precursor of kinetic form B. Thermodynamic form A matches with the third lowest energy frame based on the value of U latt determined in the crystal structure prediction (Cerius 2, COMPASS) by full-body minimization. Re-ranking the calculated frames on consideration of both Econf (Spartan 04) and U latt energies gives a perfect match of frame #1 with stable structure A. Diphenylquinone 1 is an experimental benchmark used to validate accurate crystal structure energies of the kinetic and thermodynamic polymorphs separated by -1 (～1.3kJ mol-1).
- Roy, Saikat,Banerjee, Rahul,Nangia, Ashwini,Kruger, Gert J.
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p. 3777 - 3788
(2008/02/07)
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- Quantitative cavities and reactivity in stages of crystal lattices: Mechanistic and exploratory organic photochemistry
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In continuing our research on solid-state organic photochemistry, we have been investigating the phenomenon of reactivity in stages. In this study we present new examples where the photochemical reactivity changes discontinuously at some point in the conversion. In these instances, the reaction course of the solid differs from that in solution. One example is the reaction of 2-methyl-4,4-diphenylcyclohexenone, where an unusual reaction course was encountered in the solid state; and, of two possible mechanisms, one was established by isotopic labeling. A second case is that of 4,5,5-triphenylcyclohexenone. The solid-state reaction of this enone was found to give a new photochemical transformation, the Type C rearrangement, a process that involves a δ to α aryl migration. In the case of 3-tert-butyl-5,5-diphenylcyclohexenone the Type C rearrangement occurred even in solution. The stage behavior was investigated using X-ray analysis and Quantum Mechanics/Molecular Mechanics computations. This permitted us to determine the sources and details of the stage phenomenon. The analysis revealed how a product molecule as a neighbor affects reactivity. The computations were employed to follow the course of a solid-state reaction from reactant through the succeeding stages. Additionally, the Delta-Density Analysis was utilized to ascertain the electronic nature of molecular changes. Besides product composition changing with extent of conversion, the reaction quantum yield was found to change as one stage gave way to a succeeding one.
- Zimmerman, Howard E.,Nesterov, Evgueni E.
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p. 2818 - 2830
(2007/10/03)
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- A practical preparation of 4,4-diphenylcyclohexanol: A key intermediate in the synthesis of MS-325
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A preparation of 4,4-diphenylcyclohexanol 2 is described from benzoin in five synthetic steps. The process uses readily available reagents and is suitable for manufacturing.
- Amedio Jr., John C.,Bernard, Paul J.,Fountain, Mark,Van Wagenen Jr., Gerritt
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p. 3895 - 3906
(2007/10/03)
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- The 14C radiolabelled synthesis of the cholesterol absorption inhibitor CP-148,623. A novel method for the incorporation of a 14C label in enones
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Isotopically labelled compounds play important roles in pharmaceutical research. New strategies for the synthesis of these compounds, carbon isotopes in particular, are needed due to the limited availability of labelled reagents. We have developed a novel method for the 14C labelling of enones and have applied it to the synthesis of a 14C radiolabelled version of the cholesterol absorption inhibitor CP-148,623. The key steps involve the 1,2 addition of [14C]methyl Grignard to a cyclic enone followed by the 'anomalous' ozonolysis of the resulting allylic alcohol utilizing a non-traditional basic work-up. In this two step procedure, the original enone was regenerated with a 14C carbon atom at the alpha position. After several standard chemical steps, the synthesis of [14C]CP-148,623 was completed. The method has also been applied to a series of other enones demonstrating the generality of the procedure for the introduction of carbon isotopes in enone systems.
- DeNinno, Michael P.,McCarthy, Keith E.
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p. 11007 - 11020
(2007/10/03)
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- Expedient enantiospecific synthesis of RP 73613: A new selective non-peptide NK1 antagonist
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The synthesis of RP 73613 was achieved in 13 steps with an overall yield of 12%. The strategy was based on a [3 + 2] azomethine ylid dipolar cycloaddition to generate the bicyclic framework and the asymmetric was introduced by resolution.
- Daubie, Christophe,Mutti, Stephane
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p. 7743 - 7744
(2007/10/03)
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- Type A Zwitterions and Cyclohexadienone Photochemical Rearrangements. Mechanistic and Exploratory Organic Photochemistry
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The photochemistry of 3-methoxy-4,4-diphenyl-2,5-cyclohexadienone was studied.The type A rearrangement proved to be regioselective with a preference for formation of 4-methoxy-6,6-diphenylbicyclohex-3-en-2-one relative to 5-methoxy-6,6-diphenylbicy
- Zimmerman, Howard E.,Pasteris, Robert J.
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p. 4876 - 4891
(2007/10/02)
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