The present invention relates to a compound or a pharmacologically acceptable salt thereof having excellent tissue non-specific alkaline phosphatase inhibitory activity. The present invention provides a compound represented by the formula (I): wherein R1 represents a hydrogen atom, an optionally substituted C1-6 alkyl group, or the like, R2 and R3 are the same or different and each represent a hydrogen atom, an optionally substituted C1-6 alkyl group, or the like, R4 and R5 are the same or different and each represent a hydrogen atom, an optionally substituted C1-6 alkyl group, or the like, R6 represents a hydrogen atom or the like, each R7 may be the same or different and may each represent an optionally substituted C1-6 alkoxy group or the like, X represents -CH=, -C(-R7)=, or -N=, and m represents 1 to 4, or a pharmacologically acceptable salt thereof.本發明係關於一種化合物，或是其之藥理學上可接受的鹽類，其具有優良的組織非專一性鹼性磷酸酶抑制活性。本發明提供一種由以下通式(I)所表示之化合物：其中，R1代表氫原子、可選擇性地取代之C1-6烷基、或是類似基團，R2與R3係為相同或不同，並且各別代表氫原子、可選擇性地取代之C1-6烷基、或是類似基團，R4與R5係為相同或不同，並且各別代表氫原子、可選擇性地取代之C1-6烷基、或是類似基團，R6代表氫原子或是類似基團，每個R7可以是相同或不同，並且可以各別代表可選擇性地取代之C1-6烷氧基或是類似基團，X代表示-CH=、-C(-R7)=或是-N=，並且m係代表1至4，或者是其等之藥理學上可接受的鹽類。
