A synthetic route to 9-(polyhydroxyalkyl)purines

Mercuric-ion promoted condensation of 6-chloropurine with acetylated dimethyl dithioacetals of d-ribose and d-arabinose in nitromethane afforded a separable mixture of 1′(S)-2,3,4,5-tetra-O-acetyl-1-(6-chloropurin-9-yl)-1-S-methyl-1-thio-d-ribitol (4) and its 1′(R) diastereomer, and the corresponding 1′(R)-arabinitol analogue (5); the structure of 4 was confirmed by X-ray crystallography. Desulfurization of 4 and 5 by tributylstannane in toluene gave 2,3,4,5-tetra-O-acetyl-1-(6-chloropurin-9-yl)-1-deoxy-d-ribitol (7) and the arabinitol analogue 8, convertible by the action of thiourea into the 1,6-dihydro-6-thioxopurin-9-yl analogues 9 and 10, which on deacetylation furnished the corresponding acyclic-sugar nucleosides 11 and 12.

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