Chemoselective fluorination of 2-hydroxy-3,4,7,8-tetrahydro-2H-chromen-5(6H)-ones using DAST
摘要:
In this study, diethylaminosulfur trifluoride (DAST) was successfully applied in monofluorination reactions of some trifluoromethyl substituted 2-hydroxy-2H-chromenones, employing a general, mild, and efficient methodology. The fluorinated compounds (2-fluoro-2H-chromenones) were synthesized as unique products by a chemoselective reaction in 63-81% yield despite the presence of different reactive sites subjected to reactions with DAST. (C) 2011 Elsevier Ltd. All rights reserved.
The first application of 4-alkoxy-1,1,1-trifluoroalk-3-en-2-ones in a three-component condensation protocol for the synthesis of 3-acyl-4-aryl-2-(trifluoromethyl)-2-hydroxy-3,4,7,8-tetrahydro-2H-chromen-5(6H)-ones
摘要:
The one-pot, simple and efficient three-component condensation protocol for the preparation of a series of twenty-five new 3-acy1-4-aryl-2-(trifluoromethyl)-2-hydroxy-3,4,7.8-tetrahydro-2H-chromen-5(6H)-ones, where aryl = Ph, 4-tolyl, 4-CIPh, 4-NO2Ph and 4-CHOPh, and acyl = Ac, Bz, 4-FBz, furan-2-oyl, thien-2-oyl and naphth-1-oyl, employing 1,3-cyclohexanedione, five aryl aldehydes and for the first time, six 4-alkyl(aryl/heteroaryl)-4-methoxy-1,1,1-trifluoroalk-3-en-2-ones, is described. Yields in 15-75% were obtained when the MCRs were performed in the presence of a catalytic amount of triethylamine (25 mol%) and in ethanol as solvent under reflux for 16 h. A representative X-ray diffraction data for 3-acetyl-4-phenyl-2-(trifluoromethyl)-2-hydroxy-3,4,7,8-tetrahydro-2H-chromen-5(6H)-one is also showed. (C) 2010 Elsevier B.V. All rights reserved.
Efficient entry to trifluoromethyl substituted chromanes from oxidative aromatization of tetrahydro-2H-chromen-5(6H)-ones using iodine/alcohol with conventional and microwave methods
作者:Helio G. Bonacorso、Jussara Navarini、Carson W. Wiethan、Andrizia F. Junges、Susiane Cavinatto、Rosália Andrighetto、Marcos A.P. Martins、Nilo Zanatta
DOI:10.1016/j.jfluchem.2012.06.024
日期:2012.10
This paper describes the one-pot simple and efficient oxidative aromatization reaction employing an iodine/alcohol medium for the preparation of a series of 11 new 3-acyl-2-hydroxy-5-alkoxy-4-aryl-2-(trifluoromethyl)chromanes, where acyl = Ac, Bz, furan-2-oyl; aryl = Ph, 4-NO2C6H4, 4-OCH3C6H4 and alkoxy = OMe, O-Pr-n, EtO and OBn from the respective 3-acyl-4-aryl-2-(trifluoromethyl)-2-hydroxy-3,4,7,8-tetrahydro-2H-chromen-5(6H)-ones. Yields in the range of 50-89% were obtained when the oxidative reactions were performed using both conventional thermal heating (CTH) and microwave (MW) procedures. In general, the MW method produced similar yields with shorter reaction times and easier reaction workups. As an example, a representative X-ray diffraction ORTEP for 3-benzoyl-2-hydroxy-5-methoxy-4-methoxyphenyl-2-(trifluoromethyl)chromane is also shown. (C) 2012 Elsevier B.V. All rights reserved.