57431-42-2Relevant academic research and scientific papers
Rearrangements of Cycloalkenyl Aryl Ethers
T?rincsi, Mercedesz,Nagy, Melinda,Bihari, Tamás,Stirling, András,Kolonits, Pál,Novak, Lajos
, (2016/05/24)
Rearrangement reactions of cycloalkenyl phenol and naphthyl ethers and the acid-catalyzed cyclization of the resulting product were investigated. Claisen rearrangement afforded 2-substituted phenol and naphthol derivatives. Combined Claisen and Cope rearrangement resulted in the formation of 4-substituted phenol and naphthol derivatives. In the case of cycloocthylphenyl ether the consecutive Claisen and Cope rearrangements were followed by an alkyl migration. The mechanism of this novel rearrangement reaction is also discussed.
Photogeneration of o-Quinone Methides from o-Cycloalkenylphenols
Leo, Edgar A.,Delgado, Julio,Domingo, Luis R.,Espinos, Amparo,Miranda, Miguel A.,Tormos, Rosa
, p. 9643 - 9647 (2007/10/03)
6-Alkylidenecyclohexa-2,4-dienones (o-quinone methides II) have been generated by photolysis of 2-(2′-cycloalkenyl)phenols 1 and trapped by methanol to give the ring-opened products 2. The best results have been obtained with the cyclohexenyl derivatives 1a, 1e, and 1f. In the case of the cyclopentenyl derivative 1b, photoproduct 2b was not observed, whereas only small amounts of 2c and 2d were formed from the seven- and eight-membered ring analogues 1c and 1d. Thus, ring size appears to be a key factor in the formation of o-quinone methides. This experimental result has been rationalized by means of density-functional theory (DFT) calculations. On the other hand, phenol substitution also appears to play a role in the process. Thus, electron-withdrawing groups such as CF3 (1f) accelerate the reaction, whereas the opposite is true for electron-donating groups such as OCH 3 (1e). This is explained by an excited-state intramolecular proton transfer (ESIPT) mechanism, as the above results are consistent with the excited-state acidities of the different phenols. The lack of reactivity in the case of ketone 1g, where the intersystem crossing quantum yield is close to unity, allows us to rule out a mechanism involving the triplet state.
