PROBLEM TO BE SOLVED: To provide a novel compound having bone metabolism inhibitory activity, the compound having inhibitory activity on BMP signaling through the ALK2 receptor, and also having high pharmacological activity and high safety.SOLUTION: The present invention provides a compound represented by formula (P-I) or a salt thereof, or their solvates, or a method for producing the same. The present invention also provides a bone metabolism inhibitor comprising the same as an active ingredient. [RP1 is H or OH RP2 is a substituted/unsubstituted alkyl, a substituted/unsubstituted alkenyl, a substituted/unsubstituted cycloalkyl, a substituted/unsubstituted aryl, a substituted/unsubstituted heteroaryl or the like RP3 is methyl, ethyl, 1-hydroxyethyl, butyl or benzyl RP4 is 2-ethylbutyl, cyclohexylmethyl or benzyl].SELECTED DRAWING: NoneCOPYRIGHT: (C)2017,JPO&INPIT【課題】ALK2受容体を介したBMPシグナル伝達の阻外活性を有する、薬理活性及び安全性の高い、骨代謝阻害活性を有する新規化合物の提供。【解決手段】式(P-I)で表される化合物若しくはその塩、又はそれらの溶媒和物で表される化合物若しくはその塩、又はそれらの溶媒和物、又はそれらの製造方法。それらを有効成分として含む、骨代謝阻害剤。[RP1はH又はOH;RP2は置換/非置換のアルキル、置換/非置換のアルケニル、置換/非置換のシクロアルキル、置換/非置換のアリール、置換/非置換のヘテロアリール等;RP3はメチル、エチル、1-ヒドロキシエチル、ブチル又はベンジル;RP4は2-エチルルブチル、シクロヘキシルメチル又はベンジル]【選択図】なし
