- [W(CO)5]-catalyzed endo- or exo-cycloisomerization reactions of 1,1-disubstituted 4-pentyn-1-ols: Experimental and theoretical studies
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The [W(CO)5]-catalyzed cycloisomerization reaction of 1,1-disubstituted 4-pentyn-1-ol derivatives has been studied from both, an experimental and theoretical point of view. Three different catalytic systems have been evaluated {preformed [(thf)
- Barluenga, Jose,Dieguez, Alejandro,Rodriguez, Felix,Fananas, Francisco J.,Sordo, Tomas,Campomanes, Pablo
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- Copper-catalyzed aerobic C-C bond cleavage of lactols with N-hydroxy phthalimide for synthesis of lactones
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The transformation of cyclic hemiacetals (lactols) into lactones has been achieved by Cu-catalyzed aerobic C-C bond cleavage in the presence of N-hydroxy phthalimide (NHPI). The present process is composed of a multistep sequence including a) formation of exo-cyclic enol ethers by dehydration; b) addition of phthalimide N-oxyl radical to the enol ethers followed by trapping of the resulting C-radicals with molecular oxygen to form peroxy radicals; c) reductive generation of oxy radicals and subsequent β-radical fragmentation to generate lactones.
- Tnay, Ya Lin,Chiba, Shunsuke
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p. 873 - 877
(2015/04/14)
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- Photocyclization Reactions. Part 1. Synthesis of Dihydrobenzofuranols Using Photocyclization of 2-Alkoxybenzaldehydes, 2'-Alkoxyacetophenones, 2-Formylphenoxyacetic Acids and 2-Acetylphenoxyacetic Acids
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Photocyclization reactions were carried out on 2-alkoxybenzaldehydes 1a-f, 2'-alkoxyacetophenones 2a-h, 2-formylphenoxyacetic acids 1i-l and 2-acetylphenoxyacetic acids 2i-m.Irradiation opf 1a-f and 2a-h in acetonitrile gave the corresponding dihydrobenzofuranols 3, 5 and dihydroisobenzofuranols 4, 6.Using carboxylic acids 1i-l, 2i-m as starting materials, decarboxylation occurred immediately to give the corresponding ethers 1a-d, 2a-e.Further irradiation of the solution afforded dihydrobenzofuranols 3,5 and dihydroisobenzofuranols 4, 6.Substituent effects on photocyclization and reaction pathways are discussed.
- Horaguchi, Takaaki,Tsukada, Chikara,Hasegawa, Eietsu,Shimizu, Takahachi,Suzuki, Tsuneo,Tanemura, Kiyoshi
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p. 1261 - 1272
(2007/10/02)
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