Efficient entry to trifluoromethyl substituted chromanes from oxidative aromatization of tetrahydro-2H-chromen-5(6H)-ones using iodine/alcohol with conventional and microwave methods

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-Prn, 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.

Graphical abstractA efficient one-pot oxidative aromatization using iodine/alcohol medium for the preparation of a series of 11 new 3-acyl-2-hydroxy-5-alkoxy-4-aryl-2-(trifluoromethyl)chromanes from tetrahydro-2H-chromen-5(6H)-ones by conventional heating thermal (CTH) and microwave (MW) procedures, is described.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A simple one-pot oxidative aromatization of tetrahydro-2H-chromenones in iodine/alcohol medium is successful carried-out. ► Synthesis of new series of 11 trifluoromethyl-containing chromanes by CTH and MW methods is performed. ► We developed a microwave oxidative procedure in shorter reaction times and easier reaction workups. ► The reactions can be conducted in medium methanol, ethanol, n-propanol and phenylmethanol and in yields up to 89%.