Rapid Methylation for the Synthesis of a 11C-Labeled Tolylisocarbacyclin Imaging the IP2 Receptor in a Living Human Brain

A rapid method for Pd-promoted cross-coupling of methyl iodide and tributyltin derivatives of tolylisocarbacyclins was developed with the objective of applying to the PET study on the IP2 receptor in a living human brain. The high efficiency is obtainable for both of the one-pot operation using a large excess of CuCl and the stepwise operation consisting of the initial preparation of a methylpalladium complex followed by mixing with the remaining requisite materials for the cross-coupling. The latter protocol allowed for the highly reproducible synthesis of an actual PET tracer with total radioactivity of several GBq. Several stannanes could be employed as precursors of PET tracers in this rapid cross-coupling reaction.