Phenoxazine analogs useful as amyloid aggregation inhibitors and treatment of alzheimer's disease and disorders related to amyloidosis

Disclosed are compounds of the Formula I 1 wherein: R 1 is hydrogen, lower alkyl, or cycloalkyl; R 2 is hydrogen, lower alkyl, lower alkoxy, halogen, hydroxy, aryl, heteroaryl, arylalkyl, heteroarylalkyl, arylalkoxy, heteroarylalkoxy, cyano, carboxy, alkoxycarbonyl, carbamoyl, sulfamoyl, nitro, trifluoromethyl, amino, or mono- or dialkylamino; and R 3 and R 4 independently are hydrogen, lower alkoxy, aryl, heteroaryl, halogen, hydroxy, cyano, carboxy, alkoxycarbonyl, carbamoyl, sulfamoyl, nitro, trifluoromethyl, amino, mono- or dialkylamino, or unsubstituted or substituted lower alkyl or lower alkenyl; or R 3 and R 4 together form an unsubstituted or substituted carbocyclic group. Also provided is a method of inhibiting the aggregation of amyloid proteins using a compound of Formula I and a method of imaging amyloid deposits.