Formycin analogs, synthesis

The nitrile group in 82 has been transformed into other versatile functional groups, and the derivatives so obtained have been used in the synthesis of various naturally occurring C-nucleosides and their analogs. Reduction of 82 with lithium aluminum hydride gave the amine 90 which was, in turn, transformed84 into the ureido and N-ni-troso derivatives (91-93) by treatment with nitrourea, followed by benzylation, and nitrosation.85 The diazo derivative 94, obtained by treatment of 93 with alcoholic potassium hydroxide, was a key intermediate in the synthesis of formycin B and oxoformycin B (see Section III,2,a,b). 

Grouped in this Section are the C-D-pentofuranosyl-imidazoles, -pyrazolopyrimidines, and -adenines. The last two analogs are positional isomers of formycin in which the heterocyclic moiety is attached to the sugar at an unnatural position. A rationale103 for the synthesis of this type of analog is of interest it was based on the possibility of a close structural similarity between a natural adenine nucleoside and synthetic analog with respect to available hydrogenbonding sites. 

Ugarkar, B.G., Revankar, G.R., and Robins, R.K. (1984) A simple oxidation of formycin to oxoformydn and oxoformydn B synthesis of 6-methyloxoformycin a C-nudeoside analog of doridosine. /. Heterocycl. Chem., 21,1865-1870. 

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