Provided is a compound which is represented by general formula (I) and has an excellent PHD2-inhibiting activity or a pharmaceutically acceptable salt thereof. (In the general formula (I), W, Y, R2, R3, R4 and Y4 are as defined in the description.).Se proporcionan compuestos que tienen un efecto inhibidor de PHD2 superior que son representados por la fórmula general (I): [Fórmula 274] (ver Fórmula) (en la fórmula general antes mencionada (I), W, Y, R2, R3, R4, y Y4 son como se describe arriba), o sales farmacéuticamente aceptable de los mismos.