- An increased understanding of enolate additions under mechanochemical conditions
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Very little is known about enolate addition chemistry under solver-free mechanochemical conditions. In this report, we investigated the ability to selectively form products arising from the primary, secondary, and tertiary enolates under solvent-free conditions. Using potassium tert-butoxide as the base and primary, secondary, and tertiary electrophiles, we were able to generate various enolate addition products including, 1,3,3,3-Tetraphenyl-2,2-dimethyl-1-propanone; a molecule we did not observe under traditional solution-based conditions.
- Hopgood, Heather,Mack, James
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- Building Congested Ketone: Substituted Hantzsch Ester and Nitrile as Alkylation Reagents in Photoredox Catalysis
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For the first time, 4-alkyl Hantzsch esters were used to construct molecules with all-carbon quaternary centers by visible light-induced photoredox catalysis via transfer alkylation. Up to a 1500 h-1 turnover frequency was achieved in this reaction. Reactions of 4-alkyl Hantzsch nitriles as tertiary radical donors joined two contiguous all-carbon quaternary centers intermolecularly, and this chemistry was used to synthesize a common precursor of a class of hydroxysteroid dehydrogenase inhibitors.
- Chen, Wenxin,Liu, Zheng,Tian, Jiaqi,Li, Jin,Ma, Jing,Cheng, Xu,Li, Guigen
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p. 12312 - 12315
(2016/10/07)
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- Photoinduced C-N bond cleavage in 2-azido-1,3-diphenyl-propan-1-one derivatives: Photorelease of hydrazoic acid
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(Chemical Equation Presented) Photolysis of 3-azido-1,3-diphenyl-propan-1- one (1a) in toluene yields 1,3-diphenyl-propen-1-one (2), whereas irradiation of 3-azido-2,2-dimethyl-1,3-diphenyl-propan-1-one (1b) results in the formation of mainly 2,2-dimethyl-1,3-diphenyl-propan-1-one. Laser flash photolysis (308 nm) of 1a,b in acetonitrile reveals a transient absorption (λmax = ~310 nm) due to the formation of radicals 4a and 4b, respectively, which have lifetimes of ~14 μs at ambient temperature. TD-DFT calculations (B3LYP/6-31+G(d)) reveal that the first and second excited states of the triplet ketone (T1K (n,π*) and T2K (π,π*)) in azide 1a are almost degenerate, at ~74 and 76 kcal/mol above the ground state (S0), respectively. Similarly, azide 1b has T1K and T2K 75 and 82 kcal/mol above S0, respectively. The calculated transition state for cleaving the C-N bond is located 71 and 74 kcal/mol above S0 in azides 1a and 1b, respectively. The calculated bond dissociation energies for breaking the C-N bond are 55 and 58 kcal/mol for azides 1a and 1b, respectively, making C-N bond breakage accessible from T 1K in azides 1 at ambient temperature. In comparison, the irradiation of azides 1 in argon matrices at 14 K lead to the formation of the corresponding triplet alkyl nitrenes (1-n), via intramolecular energy transfer from T2K- The characterization of 1-n was supported by isotope labeling, IR spectroscopy, and molecular modeling.
- Klima, Rodney F.,Jadhav, Abhijit V.,Singh, Pradeep N. D.,Chang, Mingxin,Vanos, Christine,Sankaranarayanan, Jagadis,Vu, Mai,Ibrahim, Nazarin,Ross, Elaine,McCloskey, Shaun,Murthy, Rajesh S.,Krause, Jeanette A.,Ault, Bruce S.,Gudmundsdottir, Anna D.
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p. 6372 - 6381
(2008/02/11)
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- Rearrangement of Ketones. Part 4. Aluminium Chloride Catalysed Rearrangement of Some 2,2-Dialkyl-1-phenyl-1-propan-1-ones
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Four α,α,α-trisubstituted acetophenones ((1):R1=R2=R3=CH3; (2):R1=R2=CH3, R3=CH2CH3; (3):R1=R2=CH3, R3=CH2Ph; (4):R1=CH3, R2=CH2CH3, R3=CH2Ph) were prepared.Ketones (1)-(4) were treated with aluminium chloride to induce rearrangement to alkyl ketones.The phenyl ketones behaved as follows: (1) gave 3-methyl-3-phenylbutan-2-one (7), (2) gave 3-methyl-3-phenylpentan-2-one (8) and 2-methyl-2-phenylpentan-3-one (9), (3) gave 3-methyl-3,4-diphenylbutan-2-one (10) and 3-methyl-1,3-diphenylbutan-2-one (11), and (4) gave 3-methyl-1,3-diphenylpentan-2-one (12), 2-methyl-1,2-diphenylpentan-3-one (13) and 3-benzyl-3-phenylpentan-2-one (14).A tentative mechanism for the rearrangement is proposed.
- Fernandez-Monreal, Maria C.,Ruiz, Maria P.
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p. 440 - 472
(2007/10/02)
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- Reaction of 3-Amino-2-alkenimines with Alkali Metals: Unexpected Synthesis of Substituted 4-(Arylamino)quinolines
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A study of the reduction of 3-amino-2-alkenimines 1 with alkali metals is reported.The nature of the alkali metal plays an important role in the course of the process.In this context, a new and simple method for the regioselective synthesis of 4-(arylamino)quinolines 4 from 1 and sodium or potassium is described.
- Barluenga, Jose,Aguilar, Enrique,Joglar, Jesus,Olano, Bernardo,Fustero, Santos
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p. 2596 - 2598
(2007/10/02)
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- Mild and Regiospecific Reduction of Masked 1,3-Dicarbonyl Derivatives to Monocarbonyl Compounds and Primary and Secodary Amines
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The regiospecific reduction of masked 1,3-dicarbonyl compounds to the corresponding saturated monocarbonyl 3 or iminic 4 compounds via 3-amino-2-alkenimines 1 is described.The formation of 3 and 4 can be explained in terms of a double reduction process from 1.A simple method for the synthesis of primary and secondary amines 6 is also described.
- Barluenga, Jose,Aguilar, Enrique,Olano, Bernardo,Fustero, Santos
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p. 1741 - 1744
(2007/10/02)
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- Thione photochemistry: Abstraction and cyclization at the β-position of aralkyl thiones from two excited states
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Excitation of a series of β-substituted aralkyl thiones either to the S2 (π,π*) state or to the S1 (n,π*) state leads to a formal insertion into the β-position and the formation of cyclopropyl thiols. The mechanisms of intramolecular
- Couture, Axel,Gomez, Jose,De Mayo, Paul
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p. 2010 - 2016
(2007/10/02)
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- "Wolf and lamb" reactions: Equilibrium and kinetic effects in multipolymer systems
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Two reagents reacting avidly with each other in solution are rendered mutually inactive by attaching each to a separate batch of insoluble polymer. Two-stage reactions in which a soluble reagent reacts first with one polymeric reagent and the product with the second polymeric reagent afford advantages over analogous reactions in solution. In acylation reactions of carbon acids, the simultaneous use of a polymeric strong base and a polymeric acylating reagent proved to be superior to the use of soluble reagents, both for bringing about quantitative acylations and for coping with undesirable side reactions. New polymeric strong bases were prepared: polymeric trityllithium, para-substituted trityllithium polymers, and polymeric lithium diisopropylamide. Active esters of polymeric o-nitrophenol and N-1-hydroxybenzotriazole were used as acylation reagents. The scope and limitation of these reactions and their application to general multiphase systems are discussed.
- Cohen,Kraus,Patchornik
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p. 7620 - 7629
(2007/10/02)
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- Substituted methanols
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The compounds are 1-aryl-1-alknyl-1-(t-butyl)-substituted methanols, e.g. 3-(2'-naphthyl)-4,4-dimethyl-pent-1-yn-3-ol, are useful as hypolipidemic agents, and are prepared by reacting a 4-aryl-pivalophenone with a metallo-alkynyl reagent under Grignard reaction conditions.
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- Hypolipidemic allene carboxylic acids
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The compounds are 4-aryl substituted buta-2,3-dienoic acids and esters thereof which may also be lower alkyl-substituted at any of the 2- and 4-positions, e.g., 4-(p-methoxyphenyl)-2-methyl-buta-2,3-dienoic acid. The compounds are useful as pharmaceutical
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