A facile and improved synthesis of tubercidin and certain related pyrrolo[2,3-d]pyrimidine nucleosides by the stereospecific sodium salt glycosylation procedure [1]

Article abstract of DOI:10.1002/jhet.5570250652

A simple synthesis of tubercidin, 7-deazaguanosine and 2'-deoxy-7-deazaguanosine has been accomplished using the sodium salt glycosylation procedure. Reaction of the sodium salt of 4-chloro- and 2-amino-4-chloro-pyrrolo[2,3-d]pyrimidine, 3 and 4, respectively, with 1-chloro-2,3-O-isopropylidene,5-O-(t-butyl)dimethylsilyl-α-D-ribofur nose gave the corresponding protected nucleosides 6 and 7 with β-anomeric configuration. Deprotection of 6 provided 8, which on heating with methanolic ammonia gave tubercidin in excellent yield. Functional group transformation of 7, followed by deisopropylidenation gave 2-aminotubercidin and 2-amino-7-β-ribofuranosylpyrrolo[2,3-d]pyrimidine-4(3H)-thione. Treatment of 7 with 1N sodium methoxide followed by exposure to aqueous trifluoroacetic acid, and ether cleavage furnished 7-deazaguanosine. 2'-Deoxy-7-deazaguanosine and 2'-deoxy-7-deaza-6-thioguanosine were also prepared by using similar sequence of reactions employing 4 and 1-chloro-2-deoxy-3,5-di-O-p-toluoyl-α-D-erythro-pentofuranose.