Preparation of aliphatic analogues of S-adenosyl-L-homocysteine and related compounds

Reaction of 9-((RS)-2,3-dihydroxypropyl)adenine (I) with p-toluenesulfonyl chloride afforded the 3-O-p-toluenesulfonyl derivative II which on treatment with 2,3-dihydropyran was transformed into the 3-O-p-toluenesulfonyl-2-O-tetrahydropyranyl derivative III. Reaction of II with sodium isobutyl mercaptide in liquid ammonia gave 9-((RS)-3-isobutylthio-2-hydroxypropyl)adenine (IV). Analogously, compound III and disodium salt of L-homocysteine after acid hydrolysis afforded S-((RS)-3-(adenin-9-yl)-2-hydroxypropyl)-L-homocysteine (V). 9-((2S,3S)-threo-2,3-O-Isopropylidene-4-O-p-toluenesulfonyl-2,3,4-trihydroxybutyl)adenine (VIII) was transformed in a similar way into the 4-isobutylthio derivative IX and the L-homocysteine derivative X. 9-Allyladenine (XII) on treatment with bromine in dioxane afforded 9-((RS)-2,3-dibromopropyl)adenine (XIII) and probably 3,9-(2-bromotrimethylene)adeninium bromide (XIV). Reaction of compounds XIII, XIV and 9-((RS)-2,3-bis-p-toluenesulfonyloxypropyl)adenine (XI) with sodium hydrogen sulfide or sodium thioacetate led invariably to polymeric compounds. 4-p-Toluenesulfonyloxymethyl-2,2-dimethyl-1,3-dithiolane (XVa) reacted with sodium salt of adenine to give 9-(X)-2,2-dimethyl-1,3-dithiolane-4-ylmethyl)adenine (XVIa); analogously, 4-p-toluenesulfonyloxymethyl-2-phenyl-1,3-dithiolane (XVb) afforded the 2,3-S-benzylidene derivative XVIb and 1-p-toluenesulfonyloxy-2,3-bis(benzylthio)propane (XIXb) gave 9-((RS)-2,3-bis(benzylthio)propyl)adenine (XIXc). Acetolysis of XVIa or reduction of XVIb with sodium in liquid ammonia led to 9-((RS)-2,3-dimercaptopropyl)adenine (XVIII) and the corresponding episulfide XVII.