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

C-labeled carbamates can be obtained in a three-component coupling reaction of primary or secondary amines with CO and C-methylation reagents. [C]Methyl-triflate mediated methylation of carbamino adducts provides the corresponding C-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 [C]GR103545.