The present invention is directed to provide a novel preparation of anticancer-active tricyclic compounds via alkyne coupling reaction. The present invention provides a process for preparing a compound of formula (Ia) or (Ib):wherein R1 is optionally substituted C1-6 alkyl, etc. W is O, S or NR2 R2 is hydrogen atom, etc., which comprises Step (a) in which a compound of formula (II):wherein R1 is the same as defined above, and a compound of formula (III) or (IV):wherein R2 is the same as defined above R3 is hydrogen atom, etc. X is halogen atom, etc., are reacted in the presence of a base, a copper catalyst and a palladium catalyst in an aprotic polar solvent.
