作者:Adam, Waldemar、Hadjiarapoglou, Lazaros、Smerz, Alex
DOI:——
日期:——
Gupta, D. R.; Kamaluddin; Naithani, Shobha, Polish Journal of Chemistry, 1990, vol. 64, # 7, p. 747 - 751
作者:Gupta, D. R.、Kamaluddin、Naithani, Shobha
DOI:——
日期:——
Synthesis and Cyclization of 1-(2-Hydroxyphenyl)-2-propen-1-one Epoxides: 3-Hydroxychromanones and -flavanones <i>versus</i> 2-(1-Hydroxyalkyl)-3-coumaranones
作者:Tamás Patonay、Albert Lévai、Csaba Nemes、Tibor Timár、Gábor Tóth、Waldemar Adam
DOI:10.1021/jo960163z
日期:1996.1.1
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.
Flavonoid epoxides. Part 20. Some unusual reactions of dimethyldioxirane (DMD) with flavonoid compounds
作者:Anthony J. Burke、W. Ivo O'Sullivan
DOI:10.1016/s0040-4020(97)00506-1
日期:1997.6
either the 2′-hydroxychalcone epoxide or the trans-2,3-dihydroflavonol could be obtained depending on the pH of the reaction mixture and the type of β-arene ring present in the substrate. Using this methodology trans-2,3-dihydroflavonols can be synthesised in far better yields than by the most commonly used method for their synthesis, that of the Algar-Flynn-Oyamada reaction. Treatment of both flavonol