Direct tritium labeling of multifunctional compounds using organoiridium catalysis. 2.

A variety of complex compounds have been labeled with tritium gas by catalytic exchange in the presence of catalyst precursors [(cod)Ir(dppe)]BF<INF>4</INF> or [(cod)Ir(py)(PCy<INF>3</INF>)]BF<INF>4</INF>. In most cases, predictable regioselectivity and high specific activities are achieved. These results are compared in some cases to the results of labeling related compounds with [(cod)Ir(PPh<INF>3</INF>)<INF>2</INF>]BF<INF>4</INF>. Prereduction of the catalyst precursors in situ with hydrogen allows the use of smaller quantities of tritium gas and reduces the amount of radioactive waste. Two or more compounds can be labeled simultaneously as mixtures then separated in the HPLC purification step to increase compound throughput. Copyright © 1999 John Wiley & Sons, Ltd.