Identification and characterization of m4 selective muscarinic antagonists

The study of a series of benzoxazine isoquinolines, which led to the identification of a potent and selective m4 muscarinic antagonist 1 is reported. [For 1 at the m4 receptor, the IC 50 = 90.7 nM; however, 1 is 72-fold (m1), 38-fold (m2), 10-fold (m3), and 82-fold (m5) more selective when compared to the other receptors.]