Synthesis of natural bromophenols with C1-4 side chain including different functional group

Natural bromophenols of (E)-4-(3-bromo-4,5-dihydroxyphenyl)but-3-en-2-one, (E)-4-(2,3-dibromo-4,5-dihydroxyphenyl)but-3-en-2-one and (E)-4-(2-bromo-4,5-dihydroxyphenyl)but-3-en-2-one (14-16) were synthesized based on the condensation of acetone with the corresponding benzaldehydes. Butyl 2-(3,5-dibromo-4-hydroxyphenyl)acetate (25) was obtained via bromination of p-methoxy phenyl acetic acid, esterification with n-BuOH and demethylation,respectively. Other natural bromophenols, 3,4,6-tribromo-5-((methylsulfonyl)methyl)benzene-1,2-diol (5), (E)-3-(2,3-dibromo-4,5-dihydroxyphenyl)-2-methylacrylaldehyde (26), 3,4-dibromo-5-(3-hydroxy-2-methylpropyl)benzene-1,2-diol (28), 3-(2,3-dibromo-4,5-dihydroxyphenyl)-2-phenylpropanoic acid (30) and 2-(2,3-dibromo-4,5-dihydroxyphenyl)acetic acid (31) were obtained from the corresponding starting compounds in order of condensation, protection, reduction, displacement, bromination and demethylation. Natural product 3,4-dibromo-5-(butoxymethyl)benzene-1,2-diol (32) was obtained starting from the corresponding aldehyde 148 by reduction, displacement, and demethylation respectively. Also, some derivatives of the natural products have been synthesized. Some compounds showed good ihibition activities against hCA-I, hCA-II, AChe and BChe