Synthesis and Cyclization of 1-(2-Hydroxyphenyl)-2-propen-1-one Epoxides: 3-Hydroxychromanones and -flavanones versus 2-(1-Hydroxyalkyl)-3-coumaranones
摘要:
Competitive alpha and beta cyclization of 2'-hydroxychalcone epoxides affords 2-(alpha-hydroxybenzyl)-3-coumaranone and/or 3-hydroxyflavanones, which depends on the conditions employed. Epoxidation of 2'-hydroxychalcones by dimethyldioxirane followed by either base- or acid-catalyzed ring closure provides a novel, general, and efficient method for the synthesis of trans-3-hydroxyflavanones, which includes also the naturally occurring derivatives. Extension of this two-step procedure to 1-(2-hydroxyphenyl)-2-alken-1-ones was also accomplished. A strong preference for alpha cyclization was observed in the case of beta-unsubstituted or -monoalkylated alpha,beta-enones, while both 2,2-dimethyl-3-hydroxychromanones and 2-(1-hydroxy-1-methylethyl)-3-coumaranones were obtained from the beta,beta-dimethylated substrates.
Formation of 2,2-dimethylchroman-4-ones during the photoinduced rearrangement of some aryl 3-methyl-2-butenoate esters. A mechanistic insight
作者:Daniela Iguchi、Rosa Erra-Balsells、Sergio M. Bonesi
DOI:10.1016/j.tet.2016.02.039
日期:2016.4
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
The present invention provides compounds, compositions thereof, and methods of using the same.
本发明提供了化合物、其组合物以及使用它们的方法。
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
作者:Cecilia Samaniego López、Rosa Erra-Balsells、Sergio M. Bonesi
DOI:10.1016/j.tetlet.2010.06.063
日期:2010.8
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