- PhI(OAc)2-promoted umpolung acetoxylation of enamides for the synthesis of α-acetoxy ketones
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Umpolung is a fundamental concept in organic chemistry, which provides an alternative strategy for the synthesis of target compounds which were not easily accessible by conventional methods. Herein, a mild and efficient PhI(OAc)2-promoted umpolung acetoxylation reactions of enamides was developed for the synthesis of α-acetoxy ketones. The reaction tolerates a wide range of functional groups and affords α-acetoxy ketones in good to excellent yields. PhI(OAc)2 serves as a source of acetoxy in the reaction.
- Chen, Ming,Zhang, Wei,Ren, Zhi-Hui,Gao, Wen-Yun,Wang, Yao-Yu,Guan, Zheng-Hui
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p. 761 - 768
(2017/06/05)
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- Iron-Catalyzed Dioxygenation of Alkenes and Terminal Alkynes by using (Diacetoxyiodo)benzene as Oxidant
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An iron-catalyzed syn-diacetoxylation of alkenes and 1,2-oxyacetoxylation of terminal alkynes has been developed using (diacetoxyiodo)benzene as oxidant. A broad range of internal and terminal alkenes, including electron-rich as well as electron-deficient alkenes, gave the desired products in good to excellent yields with high diastereoselectivity (up to >99:1 dr). In addition the high catalytic activity of iron catalysis for the 1,2-oxyacetoxylation of terminal alkynes is also reported. The roles of catalyst, oxidant and other reaction parameters were evaluated for activation of the unsaturated bond.
- Srinivas,Rawat, Vikas S.,Sreedhar, Bojja
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supporting information
p. 3587 - 3596
(2016/01/25)
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- 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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p. 10329 - 10333
(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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