C-alkenylation of pyrimidine nucleosides and their analogues

Methods for C-alkenylation of pyrimidine nucleosides and their analogues at the heterocycle are surveyed. The methods using organoelement derivatives of nucleosides (organo-mercury, -tin, -boron and -lithium), those using org anoelement derivatives of alkenes (organo-magnesium, -boron, -aluminium, -t in and -silicon), oxidative addition catalysed by palladium compounds and p hotochemical reactions are considered. The reaction conditions (the role of solvents, catalysts and co-catalysts, temperature conditions and time) are discussed. The advantages and drawbacks of various methods for the introdu ction of alkenyl groups are considered. Examples of practical application o f alkenylated derivatives of nucleosides and their analogues are presented.