Abstract Reaction of 2-phenyltrimethinium salt 1 with thiourea and subsequent reaction with chloroacetic acid afforded 5-phenyl-2 (1H)-pyrimidinone (3). Its silyl derivative 4 was condensed with 1-O-acetyl-2, 3, 5-tri-O-benzoyl-D-ribofuranose under catalysis with tin tetrachloride or trimethylsilyl trifluoromethanesulfonate to give protected nucleoside 5 together with 5', O 6-cyclo-5-phenyl-1, 3-bis-(β-D-ribofuranosyl)-6-hydroxy-5, 6-dihydro-2 ( ...
