Novel compounds that inhibit the activity of HSP90, in particular, it inhibits the function of the chaperone protein HSP90, to provide novel compounds having antitumor activity. The present invention, HSP90 inhibitor comprising a compound represented pyrazolopyrimidine compound represented by inhibiting the ATPase activity of HSP90, having antitumor activity, in formula (1) having various substituents, by the formula (1) a pharmaceutical composition comprising a compound represented by the anticancer agent containing a compound represented by the medicament comprising a compound represented by the formula (1), the formula (1), the formula (1) and the formula (1) I provides a method for the treatment of cancer using the compound.HSP90の作用を阻害する新規化合物、特に、HSP90のシャペロンタンパク質としての機能を阻害し、抗腫瘍活性を有する新規化合物を提供すること。本発明は、HSP90のATPase活性を阻害し、抗腫瘍活性を有する、各種置換基を有する式(1)で表されるピラゾロピリミジン化合物、式(1)で表される化合物を含むHSP90阻害剤、式(1)で表される化合物を含む医薬、式(1)で表される化合物を含む抗癌剤、式(1)で表される化合物を含む医薬組成物および式(1)で表される化合物を用いる癌の治療方法等を提供する。
