A method for producing a compound represented by the formula [1], a method for producing a compound represented by the formula [5a], a compound represented by the formula [4] or a salt thereof, a compound represented by the formula [5] or a A salt thereof, and a compound represented by the formula [1] or a salt thereof.式[1]で表される化合物の製造方法、式[5a]で表される化合物の製造方法、式[4]で表される化合物又はその塩、式[5]で表される化合物又はその塩、及び式[1]で表される化合物又はその塩に関する。