Stereoselective Syntheses of β-d-Ribonucleosides Catalyzed by the Combined Use of Silver Salts and Diphenyltin Sulfide or Lawesson’s Reagent

Abstract

β-d-Ribonucleosides are stereoselectively synthesized in high yields from methyl 2,3,5-tri-O-benzoyl-β-d-ribofuranosyl carbonate and trimethylsilylated nucleoside bases by the use of [diphenyltin sulfide/silver salt] or [Lawesson’s reagent/silver salt] combined catalyst system under mild conditions.

Use of Lawesson's Reagent in Organic Syntheses

“…Reaction of ribofuranosyl carbonate 328 with various trimethylsilylated bases such as uracil, thymine, theophylline, N 4 -N 4 -benzoylcytosine, N 6 -benzoyladenine, and N 2 -acetylguanine at 60-80 °C for 4-6.5 h yielded the ribonucleosides 329 from 81% to quantitative yields (Scheme 93). 438 Syntheses of R-Dand β-D-ribofuranosides 332, 335 were achieved from the reaction of ribofuranoses 330 and 333 with trimethylsilylated nucleophiles 331 and 334, respectively, applying the same LR/AgClO 4 combination (Scheme 94). 439 The reaction was performed in various solvents such as CH 2 Cl 2 , 1,2-dichloroethane, benzene, toluene, (Et) 2 O, and CH 3 CN at room temperature, which yielded the products in between 77-93% (Scheme 94).…”

“…Combinations of LR and silver salts such as AgClO 4 and AgOTf were successfully applied for the synthesis of β- d - ribonucleosides, , and in aldol and Diels−Alder reactions. Reaction of ribofuranosyl carbonate 328 with various trimethylsilylated bases such as uracil, thymine, theophylline, N 4 - N 4 -benzoylcytosine, N 6 -benzoyladenine, and N 2 -acetylguanine at 60−80 °C for 4−6.5 h yielded the ribonucleosides 329 from 81% to quantitative yields (Scheme ) …”

“…Combinations of LR and silver salts such as AgClO 4 and AgOTf were successfully applied for the synthesis of β- d - ribonucleosides, , and in aldol and Diels−Alder reactions. Reaction of ribofuranosyl carbonate 328 with various trimethylsilylated bases such as uracil, thymine, theophylline, N 4 - N 4 -benzoylcytosine, N 6 -benzoyladenine, and N 2 -acetylguanine at 60−80 °C for 4−6.5 h yielded the ribonucleosides 329 from 81% to quantitative yields (Scheme ) 93 Synthesis of Ribonucleosides Using Combination of Silver Salts and LR

94 Synthesis of Ribofuranosides Using LR/AgClO 4 Combination

95 Aldol Reactions Using LR/AgClO 4 Combination

96 Synthesis of Olefins from Phosphates or Thiophosphates

97 Synthesis of Metal Dithiolanes

98 Thionation of the Complexes 345 and 346

99 Synthesis of Thioketenyl Complexes 350

100 Synthesis of Spirotellurane Having Sulfur Atoms

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