PubMed · 13762593
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M N LIPSETT, L A HEPPEP, D F BRADLEY. 1961. Complex formation between oligonucleotides and polymers.. https://pubmed.ncbi.nlm.nih.gov/13762593/
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An efficient entry to nucleoside 3'-H-phosphonoselenoate monoesters via phosphinate intermediates was developed. It involves a reaction of suitably protected nucleosides with triethylammonium phosphinate in the presence of pivaloyl chloride, followed by selenization of the intermediate nucleoside phosphinates with triphenylphosphine selenide, to produce the corresponding nucleoside H-phosphonoselenoates in 86-92% yields.
Reaction of L-tartaric acid with thiocarbohydcrazide afforded (1R, 2S)-1,2-bis(4-amino-5-mercapto-1,2,4-triazol-3-yl)-ethane-1,2-diol (3). The functional groups in 3 allowed the construction of fused heterocycles on the 1,2,4-triazole rings, mainly of the 1,2,4-triazolo[3,4-b][1,3,4]thiadiazine type as in 4, 5, 7, 10, 13 and 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole type as in 14.
A general synthetic approach to various isoxanthopterin-nucleosides starting from 6-methyl-2-methylthio-4(3H),7(8H)-pterdinedione (1) has been developed. Ribosylation with 1-O-acetyl-2,3,5-tri-O-benzoyl-beta-D-ribofuranose via the silyl-method led to 2 and reaction with 1-chloro-2-deoxy-3,5-di-O-p-toluoyl-alpha-D-ribofuranose using the DBU-method afforded 28. Protection of the amide function at O4 by benzylation to 5 and by a Mitsunobu reaction with 2-(4-nitrophenyl)ethanol to 29 gave soluble intermediates which can be oxidized to the corresponding 2-methylsulfonyl derivatives 8 and 30, respectively. Nucleophilic displacement reactions of the highly reactive 2-methylsulfonyl functions by various amines proceeded under mild conditions to isoxanthopterin-N8-ribo- (11-17) and 2'-deoxyribomucleosides (31-33). Debenzylation can be achieve by Pd-catalyzed hydrogenation (9 to 19) and cleavage of the npe-protecting group (31, 32 to 34, 35) works well with DBU by beta-elimination.