The invention discloses a preparation method of an
antiviral drug amonevir. The method comprises the following steps: pumping sulfurized
cyclopentane-4-formyl
chloride prepared in situ and 2, 6-
dimethylaniline into a first microchannel reactor, and carrying out an amidation reaction; pumping the obtained
amide intermediate,
potassium tert-butoxide and
bromoacetic acid into a second microchannel reactor, and carrying out a second amidation reaction; pumping the generated product, 4-(1, 2, 4-
oxadiazole-3-yl)
aniline and a condensing agent into a third microchannel reactor, and carrying out a third amidation reaction; pumping the obtained product and
hydrogen peroxide into a fourth micro-channel reactor for oxidation reaction to obtain an amonevir crude product; and after the crude product is subjected to extraction, concentration and
ethanol recrystallization, an amonevir product with
liquid phase purity of 99.9% is obtained. And the
tautomer of the amonevir can be simply and efficiently separated by utilizing the detection method disclosed by the invention, and a reliable guarantee is provided for industrial production of the amonevir.