n m is 1, and R6 is a halogen atom as a substituent at the 4-position; a compound represented by the formula (II) wherein m is 1, and R6 is a trifluoromethyl group as a substituent at the 4-position; a compound represented by the formula (II) wherein m is 1, and R6 is an ethynyl group as a substituent at the 4-position; a compound represented by the formula (II) wherein m is 1, and R6 is a nitro g