A mild method for regioselective labeling of aromatics with radioactive iodine

Abstract

A novel technique to label ortho-, meta-, and para-trimethylsilyl- substituted aryl substituents with radioactive iodide is described. The method takes advantage of the ipso-directing and activating properties of trimethylsilyl substituents on the arenes. The method was demonstrated on a griseofulvin analogue with promising anticancer properties and on lidocaine, a widely used local anesthetic drug. Treatment of a trimethylsilyl precursor with Tl(OCOCF3)3 followed by Na125I consistently afforded radioactive purities over 95 % in all cases. A mild and selective method for radioiodination of aromatic compounds is described. This method is used to label three regioisomers of an analogue of griseofulvin with potent anticancer activity. The method takes advantage of the ipso-directing effect of a trimethylsilyl (TMS) substituent and is also demonstrated to work for the local anesthetic lidocaine. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.