(3,5-dichloro-2,4,6-trihydroxyphenyl)hexan-1-one + S-adenosyl-L-methionine = 1-(3,5-dichloro-2,6-dihydroxy-4-methoxyphenyl)hexan-1-one + H(+) + S-adenosyl-L-homocysteine Belongs to the class I-like SAM-binding methyltransferase superfamily. Cation-independent O-methyltransferase family. COMT subfamily.