Abstract Reaction of the silylated triazolone I with 2, 3, 5-tri-O-benzoyl-D-ribofuranosyl bromide afforded a mixture of the 4-ribosyltriazolone IXa and 2, 3-diribosyltriazolone Xa. Under the same conditions the silylated 5-methyltriazolone II gives the 4-ribosyl derivative XIa and 2-ribosyl derivative XIIa. The 4-phenyl and 4-ribosyltriazoles VII, VIII, IXa and XIa were prepared by an alternative synthesis: cyclisation of l-ethoxymethylene-, l-(l- ...