Method for palladium catalyzed carbon-carbon coulping and products

A method for the preparation of pyrimidine nucleosides modified at the 5-position of the pyrimidine ring from a pyrimidine starting material containing a halogen leaving group attached to the 5-position of the pyrimidine ring, such method comprising the steps of:

• preparing a solution of a palladium catalyst of the formula PdL.sub.3, wherein L is triphenyl phosphine (PPhd.sub.3);
• reacting said pyrimidine starting material with a tetraalkyl tin compound of the formula R'SnR.sub.3 ", wherein R" is selected from the group consisting of an alkyl of C1-C4 carbon and R' is selected from the group consisting of a carbonyl of C1-C7 C1-C7 carbons, a carbalkoxy of C1-C5 carbons, an alkenyl of C1-C3 carbons, an alkoxy of C1-C4 carbons or phenyl (C.sub.6 H.sub.5), with the palladium catalyst;
• and
• isolating and purifying said modified pyrimidine nucleoside.