Active ester resin, method for producing thereof, epoxy resin composition, cured product thereof, prepreg, laminated board, and material for circuit substrate

A method for producing an active ester resin, comprising:

• reacting a 2,6-disubstituted phenol compound and dicyclopentadiene to obtain an aromatic hydroxy compound containing a dicyclopentenyl group and represented by the following formula (7);
• and reacting the aromatic hydroxy compound and an aromatic polyvalent carboxylic acid or an acid halide thereof:
• wherein each R1 independently represents a hydrocarbon group having 1 to 8 carbon atoms, each R2 independently represents a hydrogen atom, or a dicyclopentenyl group represented by the following formula (1a) or formula (1b) and at least one R2 is the dicyclopentenyl group;
• and u represents the number of repetitions and contains a u=0 component and a u≥1 component, and an average value of the u≥1 component is a number of 1 to 5,