A New Method for Radiosynthesis of ¹¹C-Labeled Carbamate Groups and its Application for a Highly Efficient Synthesis of the Kappa-Opioid Receptor Tracer [¹¹C]GR103545

Abstract

¹¹C-labeled carbamates can be obtained in a three-component coupling reaction of primary or secondary amines with CO₂ and ¹¹C-methylation reagents. [¹¹C]Methyl-triflate mediated methylation of carbamino adducts provides the corresponding ¹¹C-labeled carbamate groups in excellent yields under mild conditions (temperatures ≤ 40°C, 2 min reaction time). The utility of the method has been demonstrated by a highly efficient radiosynthesis of [¹¹C]GR103545.