Design, Synthesis, and Pharmacokinetic Profiling of Fluorinated Reversible <i>N</i> -Alkyl Carbamate Derivatives of Psilocin for Sub-Hallucinogenic Brain Exposure

Psilocybin, the phosphorylated prodrug of psilocin, holds therapeutic promise across a range of neuropsychiatric conditions, yet its clinical utility is constrained by acute psychoactive effects. Here, we report the rational design, synthesis, and evaluation of a focused library of fluorinated reversible <i>N</i>-alkyl carbamate derivatives of psilocin aimed at reducing acute psilocin exposure and thereby limiting hallucinogenic-like effects. Carbamate bond stability was systematically modulated by varying the number and positioning of fluorine atoms on the alkyl promoiety. The resulting compounds exhibited finely tuned hydrolysis under physiological conditions. A selected lead compound (4e) showed favorable oral bioavailability and efficient brain penetration while undergoing partial bioconversion to psilocin. Notably, 4e displayed intrinsic serotonergic activity at 5-HT_2A and 5-HT_2C receptors but induced attenuated psychotropic effects relative to psilocybin. Overall, these findings highlight fluorinated carbamate chemistry as a versatile platform to control psilocin exposure and serotonergic signaling, rather than the development of a classical pharmacologically inert prodrug.