- Formation of 2,2-dimethylchroman-4-ones during the photoinduced rearrangement of some aryl 3-methyl-2-butenoate esters. A mechanistic insight
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Several aryl 3-methyl-2-butenoate esters upon irradiation lead to the formation of [1,3]-migrated photoproducts, phenol and, surprisingly 2,2-dimethylchroman-4-one derivatives. The starting photochemical reaction takes place from the singlet excited state of the ester and as a total mechanism two consecutive reaction pathways are proposed. The former involves the photo-Fries rearrangement of the esters in all the solvents studied and, depending on the proticity of the solvent, the latter involves an ESIPT process followed by thermal 6π-electrocyclic reaction and/or thermal (intramolecular oxa-Michael addition) cyclization of the ortho regioisomers photoformed. This second pathway is responsible of the formation of the 2,2-dimethylchroman-4-one derivatives.
- Iguchi, Daniela,Erra-Balsells, Rosa,Bonesi, Sergio M.
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p. 1903 - 1910
(2016/04/05)
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- A mild and convenient one-pot photochemical synthesis of chroman-4-one derivatives. the photo-Fries rearrangement of (hetero)aryl 3-methyl-2-butenoate esters under basic catalysis
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The biphasic base catalysis-mediated photo-Fries rearrangement reaction of aryl 3-methy-2-butenoate esters in room temperature cyclohexane - 10% KOH system was investigated. This mild photochemical reaction leads to the formation of chroman-4-one derivatives in good to high yield and in short reaction times (30-120 min) in a one-pot photochemical reaction. Also, the photochemical reaction, as a convenient, versatile, and general method, applies efficiently to polycyclic and heterocyclic 3-methy-2-butenaote esters.
- López, Cecilia Samaniego,Erra-Balsells, Rosa,Bonesi, Sergio M.
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supporting information; experimental part
p. 4387 - 4390
(2010/09/12)
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- Modification of hydroxybenzopyranoids: Facile deoxygenation of 2,2-dimethyl-7-hydroxy-4-chromanones and a new approach to their novel mercapto analogs
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A facile deoxygenation of a systematic series of substituted 2,2-dimethyl-7-hydroxy-4-chromanones via their sulfonate, isourea, and thiocarbamate derivatives is reported. The synthesis of novel 2,2-dimethyl-7-mercapto-4-chromanones has been accomplished b
- Sebok,Timar,Eszenyi,Patonay
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p. 6318 - 6321
(2007/10/02)
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- ON THE REACTION OF SUBSTITUTED PHENOLS AND 3-METHYLBUT-2-ENOIC ACID. A COMPARATIVE STUDY
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A systematic and comparative study of the reaction of a series of substituted phenols and 3-methylbut-2-enoic acid in zinc chloride/phosphorus oxychloride and aluminum chloride/phosphorus oxychloride reveals that the formation of phenolic esters and 2,2-dimethyl-4-chromanones is strongly influenced by the substituents, their popsition on the aromatic ring of the starting phenols.Based on our study, a mixed Friedel-Crafts and Fries rearrangement mechanism is in operation in these reactions.
- Seboek, Peter,Jekoe, Jozsef,Timar, Tibor,Jaszberenyi, Joseph Cs.
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p. 2099 - 2114
(2007/10/02)
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- On the synthesis of substituted 2,2-dimethyl1-4-chromanones and related compounds
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A systematic study of the reaction of a series of monosubstituted phenols 3 and 3-methylbut-2-enoic acid 4 in phosphorus oxychloride/zinc chloride revealed that the formation of 4-chromanones was strongly infuenced by the substituents and their position on the aromatic ring of the starting phenols.
- Seboek, Peter,Jekoe, Jozsef,Timar, Tibor,Jaszberenyi, Joseph Cs.
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p. 2791 - 2794
(2007/10/02)
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- Unsaturated N-benzopyranyllactams
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Compounds I STR1 where R1 is H, alkyl, alkoxy, CO alkyl, COOH, carboxyalkyl, CONR2, CN, NO2, alkylsulfi(o)nyl, arylsulfi(i)-nyl; R2 is H, OH, alkoxy, alkyl or alkylcarbonyl, R3 /R4 are alky
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- SYNTHESIS OF 2-SUBSTITUTED CHROMONES, CHROMANONES, AND THIO ANALOGUES USING ORGANOCOPPER REAGENTS
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Improved use of organocopper reagents provides a general route to unsymmetrical 2,2-dialkylchromanones and thiochromanones from chromones and thiochromones via a simple addition - oxidation - addition sequence
- Clarke, Paul D.,Fitton, Alan O.,Suschitzky, Hans,Wallace, Timothy W.,Dowlatshahi, Hossein A.,Suschitzki, John L.
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