- Iridium-Catalyzed Stereoselective Allylic Alkylation Reactions with Crotyl Chloride
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The development of the first enantio-, diastereo-, and regioselective iridium-catalyzed allylic alkylation reaction of prochiral enolates to form an all-carbon quaternary stereogenic center with an aliphatic-substituted allylic electrophile is disclosed. The reaction proceeds with good to excellent selectivity with a range of substituted tetralone-derived nucleophiles furnishing products bearing a newly formed vicinal tertiary and all-carbon quaternary stereodyad. The utility of this protocol is further demonstrated via a number of synthetically diverse product transformations.
- Hethcox, J. Caleb,Shockley, Samantha E.,Stoltz, Brian M.
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- Twisted Bodipy Derivative as a Heavy-Atom-Free Triplet Photosensitizer Showing Strong Absorption of Yellow Light, Intersystem Crossing, and a High-Energy Long-Lived Triplet State
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A Bodipy derivative with twisted π-conjugation system is demonstrated that shows efficient intersystem crossing (ISC) (singlet oxygen quantum yield φΔ = 55%) and a long-lived triplet state (τT = 197.5 μs) with high energy (ET1 = 1.44-1.53 eV). This is superior to the conventional heavy-atom-enhanced ISC in a reference Bodipy compound, which results in much shorter triplet state lifetime (3.3 μs) and lower triplet-state energy (1.2 eV).
- Dick, Bernhard,Dong, Yu,Zhao, Jianzhang
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- Gold-catalyzed ring-expansion through acyl migration to afford furan-fused polycyclic compounds
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A gold-catalyzed ring-expansion reaction of alkynones to access furan-fused polycyclic compounds is reported. Mechanistic studies revealed that the reaction might occur through a tandem 1,2-acyl migration/Friedel-Crafts reaction.
- Zhang, Changyuan,Jiang, Huanfeng,Zhu, Shifa
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supporting information
p. 2677 - 2680
(2017/03/10)
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- Solvent effects versus concentration effects in determining rates of base-catalyzed keto-enol tautomerization
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Solvent effects of homogeneous media (such as solvent-water mixtures) on chemical reactivity may be interpreted as due to solvent polarity and/or molecular structure of solvent molecules. In microheterogeneous media (such as aqueous micellar solutions), solvent effects on reaction rates must include concentration effects, in addition to changes in the solvent polarity of the micelle interface where the reaction is assumed to occur. In this work, we measured the rates of keto-enol tautomerization of the 2-acetylcyclohexanone (ACHE) and 2-acetyl-1-tetralone (ATLO) systems in dimethylsulfoxide (DMSO)-water mixtures and in aqueous micellar solutions with both anionic and cationic surfactants and in the presence of buffers. The results appear as an ideal framework to understand the paramount importance of the specific molecular structure of solvent molecules in determining chemical reactivity versus solvent polarity or even concentration effects. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2005.
- Iglesias, Emilia
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p. 625 - 632
(2007/10/03)
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- Photolysis of cyclic enol esters in the presence or absence of a single electron transfer photosensitizer
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The photochemistry of enol esters 1 is dominated by electrocyclic ring opening (1b → 3+4), 1,3-acyl migration (1c,d → 6c,d) and [2 + 2] dimerization (1d → 11). Photosensitization with triphenylpyrylium tetrafluoroborate (TPT) enhances formation of oxidation products (1b → 5,1c,d → 9c,d + 10c,d), presumably through the intermediacy of radical cations 1b-d+.
- Climent,Garcia,Iborra,Miranda,Primo
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p. 9289 - 9296
(2007/10/02)
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- Nitroimidazolyl pyrimidines
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Nitroimidazolyl pyrimidines of the formula SPC1 And physiologically acceptable acid addition salts thereon wherein X is alkyl of 1-4 carbon atoms, R1 and R2 each are a hydrogen atom, alkyl of 1-4 carbon atoms, phenyl triflouromethyl or a monocyclic heterocyclic ring and R3 is a hydrogen atoms, alkyl of 1-4 carbon atoms, hydroxyalkoxy of 2-4 carbon atoms or an ester thereof of an alkanocarboxylic acid of 1-4 carbon atoms, oxoalkyl of 8-6 carbon atoms, or, when R1 or R2 is phenyl, alkylene having 1-2 carbon atoms in the chain joined to the 2-position of the phenyl ring possess trichomonicidal activity.
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