Recent advances in the design and development of novel negative allosteric modulators of mGlu ₅

Negative allosteric modulators (NAMs) of metabotropic glutamate receptor subtype 5 (mGlu ₅) have remained attractive to researchers as potential therapies for a number of central nervous system related diseases, including anxiety, pain, gastresophageal reflux disease (GERD), addiction, Parkinson's disease (PD), and fragile X syndrome (FXS). In addition to the many publications with supportive preclinical data with key tool molecules, recent positive reports from the clinic have bolstered the confidence in this approach. During the 2 year time span from 2009 through 2010, a number of new mGlu ₅ NAM chemotypes have been disclosed and discussed in the primary and patent literature. A summary of several efforts representing many diverse chemotypes are presented here, along with a discussion of representative structure-activity relationships (SAR) and synthetic approaches to the templates where possible.