Synthesis of pyrazolylvinyl ketones from furan derivatives
作者:Nattawut Sawengngen、Petrakis N. Chalikidi、Sara Araby、Frank Hampel、Peter Gmeiner、Olga V. Serdyuk
DOI:10.1039/c9ob00701f
日期:——
A new protocol for the synthesis of pyrazol-5-ylvinyl ketones, e.g. pyrazole-chalcones, employing furfuryl ketones as a triketone equivalent, has been developed. The reaction occurs under mild conditions and does not require the use of expensive materials. Other important benefits include the simplicity and atom efficiency of this approach.
A selective oxidative fission of the heterocyclic nucleus of 5-methyl-2-(acylmethyl)furans or 2-(5-methyl-2-furyl)-1,3-dicarbonylcompounds by m-chloroperbenzoic acid allows the easy synthesis of the 3(2H)-furanone system.
Synthesis of Isoxazolylvinyl Ketones from Substituted Furans
作者:Olga V. Serdyuk、Frank Hampel、Vladimir T. Abaev
DOI:10.1007/s10593-020-02841-y
日期:2020.11
the preparation of isoxazolylvinyl ketones related to potential cytotoxic agents has been developed. In the first step, the reaction of furfuryl ketones with hydroxylamine hydrochloride affords the corresponding oximes. Further, the oxidative ringopening–ringclosurereaction of oximes leads to isoxazoles with an α, β-unsaturated carbonyl motif. The developed procedure is metal-free and does not require
Elimination reactions of terminal selenoxides holding an alkoxy group in the beta position, RCH-(OR)CH2SeOPh, are usually difficult and can give rise to complex reaction mixtures. We report that these reactions take place more easily whenever the oxygen atom is linked to an unsaturated group (-CH=CHR, -Ar, -CR=O, -CH=NR). These selenoxides are easily available, and the elimination reaction was employed to effect useful syntheses of both open-chain and cyclic aryl and vinyl enol ethers. Moreover, by simple isomerization with acids or bases the cyclic derivatives can be transformed into the corresponding furans. The same procedure has been employed to synthesize substituted oxazoles and thiazoles also.
Gold catalysis: benzanellation versus alkylidenecyclopentenone synthesis
作者:A. Stephen K. Hashmi、Michael Wölfle
DOI:10.1016/j.tet.2009.08.074
日期:2009.10
A series of different furan-yn-ols were prepared by a three-step sequence. Their reaction with Gagosz's catalyst Ph3PAuNTf2 depends strongly on the substitution pattern of the Substrate and the quality of the leaving group. Benzofurans, alkylidenecyclopentenones or Meyer-Schuster type products can be obtained. Improving the leaving group quality leads to the preferred formation of benzofurans. (C) 2009 Elsevier Ltd. All rights reserved.