- Photodecarboxylation of Substituted Naphthylmethyl Arylacetate Esters: Synthesis of Naphthylarylethanes
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The synthesis of naphthylarylethanes via the photodecarboxylation of naphthylmethyl arylacetate esters is reported where the aryl group is able to stabilize a charge transfer reaction. The reaction proceeds via intramolecular charge transfer from the donor to acceptor, thereby enhancing a pathway to produce, within the solvent cage, the desired diarylethane products. These in-cage naphthylarylethanes are produced in good yields, in a single photochemical step, with the use of cyclohexane as a solvent providing optimal yields.
- Hilborn, James W.,Moya-Barrios, Reinaldo,Thompson, Alison
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p. 11992 - 11999
(2019/10/02)
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- Photochemistry of substituted 1-naphthylmethyl esters of phenylacetic and 3-phenylpropanoic acid: Radical pairs, ion pairs, and marcus electron transfer
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The ring-subtituted 1-naphthylmethyl esters of phenylacetic (3a-k) and 3-phenylpropanoic (5a-c) acid have been photolyzed in methanol solvent. The major products of these reactions are derived from two critical intermediates, the 1-naphthylmethyl radical/acyloxy radical pair and the 1-naphthylmethyl cation/carboxylate anion ion pair. The radical pair results in formation of the in-cage coupled products 8a-k and 10a-c after loss of carbon dioxide from the acyloxy radical. The ion pair leads to the methyl ethers 6a-k and the carboxylic acids 7 and 9. The competition between the radical and ionic pathways is very dependent upon the substituents on the naphthalene ring. Analysis of these substituent effects results in a proposed mechanism of initial homolytic cleavage of the carbon-oxygen bond of the ester from the excited singlet state. This radical pair then partitions between two pathways: decarboxylation of the acyloxy radical and electron transfer converting the radical pair to the ion pair. The rates of electron transfer are shown to fit Marcus theory in both the normal and the inverted region.
- DeCosta, Dayal P.,Pincock, James A.
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p. 2180 - 2190
(2007/10/02)
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- 187. Acid-Catalyzed Cleavage of 1,4-Dimethyl-1,4-dihydronaphthalene 1,4-Endoperoxide. Reactivity of the Resulting Hydroxyperoxy Carbocation with Nucleophiles
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In the presence of acids, 1,4-dimethyl-1,4-dihydronaphthalene 1,4-endoperoxie readily reacts with nucleophiles to produce methyl- and ring-substituted naphthalenes in high yields.The regioselectivity observed depends on the nucleophile.The key intermediate is shown to be the corresponding hydroperoxy carbocation which could be intercepted in certain cases prior to aromatization.The hydroperoxide also undergoes Hock-type cleavage and dimerization giving 2,3-dihydro-1-benzoxepins, 4-methyl-1-naphthol, and 1,2,5,6-tetraoxocane as by-products.
- Jefford, Charles W.,Rossier, Jean-Claud,Kohmoto, Shigeo,Boukouvalas, John
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p. 1804 - 1814
(2007/10/02)
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- Functionalization of the Methyl Group of 1,4-Dimethyl-1,4-dihydronaphthalene-1,4-endoperoxide
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The acid-catalysed cleavage of 1,4-dimethyl-1,4-dihydronaphthalene-1,4-endoperoxide gives the 4-hydroxy, methoxy, trifluoroacetoxy, formyloxy, bromo, and chloro methyl derivatives of 1-methylnaphthalene in yields of 36, 38, 52, 76, 77, and 100percent respectively when water, methanol, trifluoroacetic, formic, hydrobromic, or hydrochloric acids are used as reagents.
- Jefford, Charles W.,Rossier, Jean-Claude,Kohmoto, Shigeo,Boukouvalas, John
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p. 1496 - 1497
(2007/10/02)
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