Efficient Synthesis of Chromones with Alkenyl Functionalities by the Heck Reaction
作者:Tamás Patonay、Attila Vasas、Attila Kiss-Szikszai、Artur M. S. Silva、José A. S. Cavaleiro
DOI:10.1071/ch10295
日期:——
the Heck reaction in the field of chromones has been demonstrated. Bromochromones with the halogen atom in their rings A and B were reacted with various terminal alkenes to give hitherto unknown alkenyl‐substituted chromones. Reactivity of the substrates was found to markedly depend on the position of the bromineatom. Under phosphine‐free conditions using a phase‐transfer catalyst additive (tetrabutylammonium
An efficient and diastereoselective synthetic method for preparing (E)-3-styrylchromones has been developed by the reaction of chromone-3-carboxaldehyde with phenylacetic acids in the presence of potassium tert-butoxide under classical heating conditions or microwave irradiation. The Knoevenagel-type reaction followed by a decarboxylation was faster under microwave conditions.
Microwave-assisted Suzuki–Miyaura and Heck–Mizoroki cross-coupling reactions of aryl chlorides and bromides in water using stable benzothiazole-based palladium(II) precatalysts
作者:Kamal M. Dawood
DOI:10.1016/j.tet.2007.07.029
日期:2007.9
catalytic activity of benzothiazole-based Pd(II)-complexes was evaluated in Suzuki–Miyaura and Heck–Mizoroki C–C cross-coupling reactions of arylchlorides and bromides with olefins and arylboronic acids both under thermal as well as microwaveirradiation conditions in water. The factors affecting the optimization of such reactions as well as the reusability of the Pd-precatalysts are studied.
A Brønsted acid controlled Diels-Alder reaction of 3-vinylchromones with arynes has been developed. By employing different kinds and amounts of acid, 9-aryl-9H-xanthen-9-ols or ortho-hydroxybenzophenones could be controllably furnished in good yields in an atom- and step-economic manner.
A concise and efficient photoinduced rearrangement of (E)-3-arylvinyl-4H-chromen-4-ones for the synthesis of benzoaryl-5-yl(2-hydroxyphenyl)methanones is described. Benzoaryl-5-yl-(2-hydroxyphenyl)methanones were obtained in 77–95% yields via the irradiation of (E)-3-arylvinyl-chromones in the 95% EtOH with a high-pressure mercury lamp at room temperature under Ar atmosphere. The reported method provides