Highly basic tris(diethylamino)-N-methylphosphazene was used for mono- and difluoromethylation of diethyl N-acetylaminomalonate by CH2BrF or CHClF2 in dichloromethane at -40 degrees C. Acidic hydrolysis of fluoromethylated products afforded fluoro- and difluoroalanine, respectively. (C) 2000 Elsevier Science S.A. All rights reserved.