Synthesis of a series of novel 3,9-disubstituted phenanthrenes as analogues of known N-methyl-D-aspartate receptor allosteric modulators

Abstract 9-Substituted phenanthrene-3-carboxylic acids have been reported to have allosteric modulatory activity at the N-methyl-d-aspartate (NMDA) receptor. This receptor is activated by the excitatory neurotransmitter l-glutamate and has been implicated in a range of neurological disorders such as schizophrenia, epilepsy and chronic pain, and in neurodegenerative disorders such as Alzheimer's disease. Herein, the convenient synthesis of a wide range of novel 3,9-disubstituted phenanthrene derivatives starting from a few common intermediates is described. These new phenanthrene derivatives will help to clarify the structural requirements for allosteric modulation of the NMDA receptor.