Ocular Hypotensive Response in Nonhuman Primates of (8<i>R</i>)‑1-[(2<i>S</i>)‑2-Aminopropyl]-8,9-dihydro‑7<i>H</i>‑pyrano[2,3‑<i>g</i>]indazol-8-ol a Selective 5‑HT₂ Receptor Agonist

Recently, it has been reported that 5-HT₂ receptor agonists effectively reduce intraocular pressure (IOP) in a nonhuman primate model of glaucoma. Although 1-[(2<i>S</i>)-2-aminopropyl]­indazol-6-ol (AL-34662) was shown to have good efficacy in this nonhuman primate model of ocular hypertension as well as a desirable physicochemical and permeability profile, subsequently identified cardiovascular side effects in multiple species precluded further clinical evaluation of this compound. Herein, we report selected structural modifications that resulted in the identification of (8<i>R</i>)-1-[(2<i>S</i>)-2-aminopropyl]-8,9-dihydro-7<i>H</i>-pyrano­[2,3-<i>g</i>]­indazol-8-ol (<b>13</b>), which displayed an acceptable profile to support advancement for further preclinical evaluation as a candidate for proof-of-concept studies in humans