- 2,5-Dimethylphenacyl esters: A photoremovable protecting group for carboxylic acidsi
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Irradiation of 2,5-dimethylphenacyl (DMP) esters (la-c) in benzene or cyclohexane solutions produces the corresponding free carboxylic acids (2a-c) in high chemical yields, along with 6-methyl-l-indanone (3). In methanol, 2-(methoxymethyl)-5-methylacetophenone (4) is formed as a coproduct. Quantum yields for the photorelease of the DMP group are higher in nonpolar solvents, 0.2, than in methanol, (f> 0.1. The photoreaction is initiated by efficient photoenolization, 01. Three transient intermediates were identified by laser flash photolysis of la, the triplet-state photoenol and the two ground-state photoenols of Z and E configuration. Release of the acids 2a-c occurs predominantly from the E isomer, which has a lifetime of about 2 ms in methanol and 0.5 s in benzene solution. The present data are essential for potential applications of the DMP moiety as a photoremovable protecting group in organic synthesis or biochemistry ( caged compounds ).
- Zabadal, Miroslav,Pelliccioli, Anna Paola,Klan, Petr,Wirz, Jakob
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- The identification of indacaterol as an ultralong-acting inhaled β2-adrenoceptor agonist
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Following a lipophilicity-based hypothesis, an 8-hydroxyquinolinone 2-aminoindan derived series of β2-adrenoceptor agonists have been prepared and evaluated for their potential as inhaled ultralong-acting bronchodilators. Determination of their activities at the human β2-adrenoceptor receptor showed symmetrical substitution of the 2-aminoindan moiety at the 5- and 6-positions delivered the targeted intermediate potency and intrinsic-efficacy profiles relative to a series of clinical reference β2-adrenoceptor agonists. Further assessment with an in vitro superfused electrically stimulated guinea-pig tracheal-strip assay established the onset and duration of action time courses, which could be rationalized by considering the lipophilicity, potency, and intrinsic efficacy of the compounds. From these studies the 5,6-diethylindan analogue indacaterol 1c was shown to possess a unique profile of combining a rapid onset of action with a long duration of action. Further in vivo profiling of 1c supported the long duration of action and a wide therapeutic index following administration to the lung, which led to the compound being selected as a development candidate.
- Baur, Fran?ois,Beattie, David,Beer, David,Bentley, David,Bradley, Michelle,Bruce, Ian,Charlton, Steven J.,Cuenoud, Bernard,Ernst, Roland,Fairhurst, Robin A.,Faller, Bernard,Farr, David,Keller, Thomas,Fozard, John R.,Fullerton, Joe,Garman, Sheila,Hatto, Julia,Hayden, Claire,He, Handan,Howes, Colin,Janus, Diana,Jiang, Zhengjin,Lewis, Christine,Loeuillet-Ritzler, Frederique,Moser, Heinz,Reilly, John,Steward, Alan,Sykes, David,Tedaldi, Lauren,Trifilieff, Alexandre,Tweed, Morris,Watson, Simon,Wissler, Elke,Wyss, Daniel
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supporting information; experimental part
p. 3675 - 3684
(2010/07/16)
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- Photochemistry of 2-alkoxymethyl-5-methylphenacyl chloride and benzoate
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Irradiation of 2-(alkoxymethyl)-5-methyl-α-chloroacetophenones (1a-c) and 2-(methoxymethyl)-5-methylphenacyl benzoate (1d) in dry, nonnucleophilic solvents afforded 3-alkoxy-6-methylindan-1-ones (3a-c) in very high chemical yields. 3-Methylisobenzofuran-1
- Plistil, Lukas,Solomek, Tomas,Wirz, Jakob,Heger, Dominik,Klan, Petr
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p. 8050 - 8058
(2007/10/03)
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- 2,5-Dimethylphenacyl as a New Photoreleasable Protecting Group for Carboxylic Acids
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(Matrix Presented) The 2,5-dimethylphenacyl chromophore, a new photoremovable protecting group for carboxylic acids, is proposed. Direct photolysis of various 2,5-dimethylphenacyl esters in benzene or methanol at 254-366 nm leads to the formation of the corresponding carboxylic acids in almost quantitative isolated yields. The photodeprotection is based on efficient intramolecular hydrogen abstraction without the necessity of introducing a photosensitizer.
- Klan, Petr,Zabadal, Miroslav,Heger, Dominik
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p. 1569 - 1571
(2007/10/03)
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- Photoenolization with α-Chloro Substituents
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Irradiation of a methanol solution of 2,5-dimethyl-α-chloropropiophenone (1a) produces 2,6-dimethyl-1-indanone (2a), 2-(methoxymethyl)-5-methylpropiophenone (3a), 2,5-dimethylpropiophenone (4a), and methyl 2-(2,5-dimethylphenyl)propionate (5a).It is proposed that the first two products arise from hydrogen abstraction followed by chlorine loss, the latter two from initial loss of chlorine.Making the chlorine-bearing carbon primary suppresses the formation of the latter two products, while maintaining the carbonyl nearly planar with the ring suppresses all product formation.Other examples are presented.
- Bergmark, William R.,Barnes, Curtis,Clark, Jeffrey,Paparian, Seth,Marynowski, Susan
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p. 5612 - 5615
(2007/10/02)
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