Synthesis of DDNP Analogs with an Aromatic Ring Attached via an Ethylidene Tether

The parent DDNP molecule was modified in such a manner that an aromatic or heteroaromatic ring was attached through an ethylidene tether. A series of analogs of FDDNP, a molecular probe for protein aggregate deposition in the central nervous system, was obtained. These analogs exhibit similar optical properties as DDNP/FDDNP and thus fulfill the optical requirements for successful application in fluorescence microscopy. The introduced aromatic ring offers an additional opportunity for p-interaction between the molecule and protein aggregates.