2-(Fluoro-) and 2-(methoxyanilino)-1,4-naphthoquinones. Synthesis and mechanism and effect of fluorine substitution on redox reactivity and NMR
Journal of Fluorine Chemistry
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The influence of catalysts on the addition of methoxy- and fluoroanilines with 1,4-naphthoquinone to give methoxy- and fluoro-substituted 2-(anilino)-1,4-naphthoquinones was investigated. In the absence of a catalyst, this reaction requires long times and low yields of the anilino derivatives are obtained accompanied with the formation of several secondary products. Excellent yields were obtained with a catalytic amount of a Lewis acid with strong oxidation properties such as CeCl3 or FeCl3. Excellent yields were also obtained when the reaction was performed with a Brønsted acid/oxidant mixture such as AcOH/Cu(OAc)2. This addition reaction was also investigated using microwave irradiation. A discussion on reaction conditions and mechanism is presented. The 1H and 13C NMR data of all the derivatives were analyzed and assigned using two dimensional 1H-13C gHSQC and gHMBC NMR experiments. The effect of fluorine substitution on redox and NMR properties was also investigated.