The regioselective synthesis of the substituted (4
R
*,10a
R
*)-4-aryltetrahydro-2
H
-chromeno2,3-
d
pyrimidin-2-ones, -pyrimidine-2-thiones and (4
R
*,5
R
*,6
R
...*)-5-acetyl-6-aryl-4-(2,4-dihydroxyphenyl)hexahydropyrimidin-2-ones, -hexahydropyrimidine-2-thiones by the reaction of the appropriate 5-acetyl-4-aryldihydropyrimidin-2-ones and -pyrimidine-2-thiones with 1,3-benzenediols was described. A plausible mechanism of the acid catalyzed rearrangement of resorcinol-substituted hexahydropyrimidin-2-ones and -pyrimidine-2-thiones to chromeno2,3-
d
pyrimidin-2-ones and -pyrimidine-2-thiones, respectively, was suggested.
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•Resorcinol and some derivatives are alternative substrates of tyrosinase.•The o-quinone originated in each reaction isomerizes to a stable p-quinone.•The kinetic characterization of ...each compound has been realized.
The action of tyrosinase on resorcinol and some derivatives (4-ethylresorcinol, 2-methylresorcinol and 4-methylresorcinol) was investigated. If the catalytic cycle is completed with a reductant such as ascorbic acid or an o-diphenol such as 4-tert-butylcatechol, these compounds act as substrates of tyrosinase in all cases. The reaction can also be carried out, adding hydrogen peroxide to the medium. All the above compounds were characterized as substrates of the enzyme and their kinetic constants, KM (Michaelis constant) and kcat (catalytic constant) were determined.
Measurement of the activity of the enzyme after pre-incubation with resorcinol, 4-ethylresorcinol or 4-methylresorcinol points to an apparent loss of activity at short times, which could correspond to an enzymatic inactivation process. However, if the measurements are extended over longer times, a burst is observed and the enzymatic activity is recovered, demonstrating that these compounds are not suicide substrates of the enzyme. These effects are not observed with 2-methylresorcinol. The docking results indicate that the binding of met-tyrosinase with these resorcinols occurs in the same way, but not with 2-methylresorcinol, due to steric hindrance.
Phosphonoethylated amino acetals were synthesized for the first time by reacting vinylphosphonates with α- and γ-aminoacetals. The reaction of 2-methylresorcinol with the acetals in ethanol in the ...presence of hydrochloric acid afforded the first representative of diarylbutylamines containing β-aminoethylenephosphoryl fragment.
The reaction of 1-(2,2-dimethoxyethyl)-1,3,3-trimethylurea with 2-methylresorcinol in dioxane in the presence of trifluoromethanesulfonic acid affords a new type of imidazolidin-2-ones,
viz.
, ...5-(2,4-dihydroxy-3-methylphenyl)-1,1,3-trimethyl-2-oxoimidazolidinium triflate containing an endocyclic ammonium nitrogen atom.
