Palladium Catalysis in the Preparation of Alkynylpyrimidines.

Abstract
4-Ethynyl derivatives of 5-chloro-2-methylthiopyrimidines, and of 5-chloro-2(1H)-pyrimidinones as trimethylsilyl derivatives, have been prepared by cross-coupling reactions between 4-iodopyrimidines and acetylenes using palladium catalysis. Reactions for the conversion of the coupling products to 2(1H)-pyrimidinones are described. Simple 4-alkynyl derivatives of 2(1H)-pyrimidinones are sensitive to alkali, especially the free acetylenic derivative. Phenyl substitution of the acetylenic function gave chemically stable compounds.