NMR of a series of novel hydroxyflavothiones.

Alkylated hydroxyflavothiones, namely flavothione, 5-hydroxyflavothione, 5,7-dihydroxyflavothione (chrysinthione), 7-dodecyloxy-5-hydroxyflavothione, 7-butyloxy-5-hydroxyflavothione, 2',3,4',7-tetramethoxy-5-hydroxyflavothione, 3,3',4',7-tetramethoxy-5-hydroxyflavothione, 7-butyloxy-4',5-dihydroxyflavothione and 7-butyloxy-4',5-hydroxyflavanonethione have been synthesized from the corresponding hydroxyflavones in two steps, alkylation of the non-hydrogen-bonded hydroxyl groups by bromoalkanes or dimethyl sulfate followed by conversion of the carbonyl group to a thione using Lawesson's Reagent under microwave irradiation and solvent-free conditions. Part of the alkylated flavanone, 7-butyloxy-4',5-dihydroxyflavanone, was oxidized during the treatment with Lawesson's reagent to yield a second product 7-butyloxy-4',5-dihydroxyflavothione in addition to the target product butyloxy-4',5-hydroxyflavanonethione. Deuterium isotope effects on 13C chemical shifts have been measured in hydroxyflavones, isoflavones, flavanones and the thio analogs.