Acetoxy-2-thiopyridone

In another version of this method, the radical generated by radical exchange from the aryl telluride carbohydrate 83 and the N-acetoxy-2-thiopyridone affords, after intramolecular cyclization and desulfanylation, the polyhydroxylated and phosphorylated pseudo sugar 84 [54] (Scheme 23). 

In accordance with the following scheme the hydroxyaldehyde A was submitted to a Wittig olefmation followed by the mesylation of the hydroxyl group to give the a,)3-unsat-urated compound B which was in turn converted into the telluride C by treatment with the appropriate aryltellurolate. Irradiation of C in the presence of iV-acetoxy-2-thiopyridone gave rise to the cyclic compound D. 

The Gif group have used methyl radicals formed by photolysis of N-acetoxy-2-thiopyridone to generate 5 -radicals in nucleoside systems. The formation of the 5, 8-cyclopurine nucleoside (26) by this method is shown in Scheme 4, as is a similar reaction in the pyrimidine series. In this case (27) could be reductively desulfurized with Raney nickel. The tellurides used as radical precursors were formed by displacement of 5 -0-mesylates.27 Free-radical cyclization was also employed in a synthesis of 6,l -propanouridine (29) from the known anhydronucleoside (28) as indicated in outline in Scheme 5.28... 

To a solution of Af-hydroxy-2-thiopyridone (140 mg, 1.1 mmol) and pyridine (0.1 ml) in toluene (10 ml) was added a solution of 3(3-acetoxy-ll-ketobisnorallocholanic acid... 

The same reaction can be carried out by the dropwise addition of 3p-acetoxy-ll-ketobisnorallocholanic acid chloride (1 mmol) in toluene (5 ml) to a refluxing solution of dried sodium salt of V-hydroxy-2-thiopyridone (1.2 mmol), 4-(dimethylamino)pyridine (0.1 mmol), and tert-BuSH (4.5 mmol) in toluene (20 ml), over 15 min [1]. 

Diethylaminoethanol added dropwise to a refluxing soln. of 3-acetoxyacetyl-acetone and cyanothioacetamide in ethanol 3-acetoxy-2,4-dimethyl-5-cyano-6-thiopyridone. Y 88%. F. e. s. U. Schmidt and H. Kubitzek, B. 95, 1559 (1960). 

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