Abstract: The present invention provides a compound represented by formula (I) that can image monoamine oxidase-B with high specificity and selectivity for monoamine oxidase-B and with good sensitivity, or a pharmaceutically acceptable salt or solvate thereof.

Abstract: The present invention provides a phosphonium compound of formula (II). Also provided is a method for producing a quaternary phosphonium compound labeled with a positron emitting radionuclide, the method comprising the step of reacting an electrophile of formula (I): X1-CH2-A1 with triphenylphosphine having one or more radionuclide-labeled substituents on the benzene ring to give a quaternary phosphonium salt.

Abstract: An object of the present invention is to provide a probe for imaging a ?-sheet structure protein which can be used for the diagnosis of conformational diseases, particularly disease (tauopathy) having a cardinal symptom such as intracerebral accumulation of tau protein, for example, Alzheimer's disease. Another object of the present invention is to provide a compound which is highly specific to tau and can image tau with satisfactory sensitivity, and also has high brain transition, low or non-recognized bone-seeking properties and low or non-recognized toxicity. According to the present invention, the above problems are solved by providing a compound of a formula I (wherein A, R1, R2, R3, R4, R5, R6, Ra and Rb are as defined in the present description) or a pharmaceutically acceptable salt or solvate thereof.

Abstract: An object of the present invention is to provide a probe for imaging a ?-sheet structure protein which can be used for the diagnosis of conformational diseases, particularly disease (tauopathy) having a cardinal symptom such as intracerebral accumulation of tau protein, for example, Alzheimer's disease. Another object of the present invention is to provide a compound which is highly specific to tau and can image tau with satisfactory sensitivity, and also has high brain transition, low or non-recognized bone-seeking properties and low or non-recognized toxicity. According to the present invention, the above problems are solved by providing a compound of a formula I (wherein A, R1, R2, R3, R4, R5, R6, Ra and Rb are as defined in the present description) or a pharmaceutically acceptable salt or solvate thereof.

Abstract: An object of the present invention is to provide a probe for imaging a ?-sheet structure protein which can be used for the diagnosis of conformational diseases, particularly disease (tauopathy) having a cardinal symptom such as intracerebral accumulation of tau protein, for example, Alzheimer's disease. Another object of the present invention is to provide a compound which is highly specific to tau and can image tau with satisfactory sensitivity, and also has high brain transition, low or non-recognized bone-seeking properties and low or non-recognized toxicity. According to the present invention, the above problems are solved by providing a compound of a formula I (wherein A, R1, R2, R3, R4, R5, R6, Ra and Rb are as defined in the present description) or a pharmaceutically acceptable salt or solvate thereof.

Abstract: An object of the present invention is to provide a compound represented by formula (I) which is highly specific to tau and can image tau with satisfactory sensitivity, and also has high brain transition, low or non-recognized bone-seeking properties and low or undetected toxicity.

Abstract: An object of the present invention is to provide a probe for imaging a ?-sheet structure protein which can be used for the diagnosis of conformational diseases, particularly disease (tauopathy) having a cardinal symptom such as intracerebral accumulation of tau protein, for example, Alzheimer's disease. Another object of the present invention is to provide a compound which is highly specific to tau and can image tau with satisfactory sensitivity, and also has high brain transition, low or non-recognized bone-seeking properties and low or non-recognized toxicity. According to the present invention, the above problems are solved by providing a compound of a formula I (wherein A, R1, R2, R3, R4, R5, R6, Ra and Rb are as defined in the present description) or a pharmaceutically acceptable salt or solvate thereof.

Abstract: An object of the present invention is to provide a probe for imaging a ?-sheet structure protein which can be used for the diagnosis of conformational diseases, particularly disease (tauopathy) having a cardinal symptom such as intracerebral accumulation of tau protein, for example, Alzheimer's disease. Another object of the present invention is to provide a compound which is highly specific to tau and can image tau with satisfactory sensitivity, and also has high brain transition, low or non-recognized bone-seeking properties and low or non-recognized toxicity. According to the present invention, the above problems are solved by providing a compound of a formula I (wherein A, R1, R2, R3, R4, R5, R6, Ra and Rb are as defined in the present description) or a pharmaceutically acceptable salt or solvate thereof.

Abstract: An object of the present invention is to provide a probe for imaging a ?-sheet structure protein which can be used for the diagnosis of conformational diseases, particularly disease (tauopathy) having a cardinal symptom such as intracerebral accumulation of tau protein, for example, Alzheimer's disease. Another object of the present invention is to provide a compound which is highly specific to tau and can image tau with satisfactory sensitivity, and also has high brain transition, low or non-recognized bone-seeking properties and low or non-recognized toxicity. According to the present invention, the above problems are solved by providing a compound of a formula I (wherein A, R1, R2, R3, R4, R5, R6, Ra and Rb are as defined in the present description) or a pharmaceutically acceptable salt or solvate thereof.