Nucleoside Syntheses, XXIII¹⁾ On the Mechanism of Nucleoside Synthesis

During the silyl‐Hilbert‐Johnson nucleoside synthesis with Friedel‐Crafts catalysts three processes occur simultanously: The formation of the electrophilic sugar cation. The σ‐complex formation between th silylated base and the Friedel‐Crafts catalyst and finally. The reaction of the electrophilic sugar cation with the silylated base to the nucleoside. Mode and rate of σ‐complex formation between the silylated base and the Friedel‐Crafts catalysts were monitored by 13 C‐NMR. The probable mechanism of nucleoside synthesis and the factors which influence course and yield of nucleoside synthesis are discussed.