abstract |
Disclosed is a compound of formula (1), or a salt thereof, wherein A1-4 are each carbon or nitrogen, with at least one being carbon, R3 is -(O)n(CH2)mR1, wherein m is 0-4, n is 0-1, and R1 is as defined in the specification. The compound is disclosed to be a low-toxic diagnostic agent for Alzheimer's disease. |