PURPOSE: To advantageously obtain the subject compound by adding a carbonyl compound to a samarium complex obtained from a reaction of an organic halide, aromatic isonitrile and a salt of divalent samarium at a specific condition and reacting with acetic anhydride or water.

CONSTITUTION: A compound expressed by the formula RX1 (R is organic group; X1 is Cl or Br) is reacted with a compound expressed by the formula R0CN (R0 is aromatic group having substituting group at least one ortho-position, preferably 2,6-xylyl) and a salt expressed by the formula SmX2 2 (X2 is Cl, Br or I) in a nonprotonic solvent in the presence of hexamethylphosphoramide to obtain a samarium complex and resultant complex is reacted with a compound expressed by formula I (R1 and R2 are H or organic group) to obtain a carbonyl compound adduct. Then, said adduct is reacted with a compound expressed by the formula R3 2 O (R3 is H or acetyl) to advantageously afford the aimed compound expressed by formula II using a samarium complex as an equivalent body of acyl anion without requiring reactions of multi-stage.