Pyrimidine Nucleosides. I. A New Route for the Synthesis of Thymine Nucleosides¹

Chemistry of the Nucleotides

“…The general method, first extended to the synthesis of pyrimidine nucleosides by Fox and co-workers (25), has also been applied with considerable success to the synthesis of a number of N3-glycosyl pyrimidines, including 3'-and 5' -amino nucleosides (26) and 5' fiuoro nucleosides (14), in addition to the naturally occurring nucleosides (27). In the main, the rule proposed by Baker an , d stating that in this type of synthesis the stereochemistry of the glycosyl linkage is controlled by the 2-acyloxy group of the sugar, resulting in forma tion of a nucleoside containing a CI_C2 trans configuration regardless of the original configuration at Cl-C2 of the sugar, has been shown to have a wide validity and, indeed, is now used asa proof of configuration.…”

Reactions of Transglycosylation in the Nucleoside Chemistry

“…In the second step, the O-glycoside (18) undergoes transglycosylation to the N 1 -nucleoside (19), a thermodynamic product of glycosylation. Stability of the pyrimidine O-glycosides and the influence of catalysts, solvents, substituents, size of the sugar ring, etc., on the O N migration have been studied in detail [1][2][3][21][22][23][24][25][26][27] and are reviewed by Fox, Hollenberg and Watanabe [6]. Most importantly, the isomerization proceeds via the 1,O 2 -bisribofuranosyl intermediate (20), and compounds of this type have been isolated from reaction mixtures and fully characterized [28,29].…”

Syntheses and properties of pterin ribonucleosides

“…Lumazine [2][3][4][5][6][7][8][9][10][11] and isopterin nucleosides 12 can be regarded as structural analogs of the pyrimidine nucleosides whereas the many pteridin-7-one N 8 -nucleosides [13][14][15][16][17][18][19][20][21][22][23] are structurally related to the purine nucleosides. The syntheses could be achieved either by a classical Hilbert-Johnson reaction 24 , the mercury salt method by Fox and Davoll 25 , the Hilbert-Johnson-Birkofer silyl procedure 26,27 or the silyl variant by Vorbrüggen 28 .…”

“…The ribosylation reaction have also been extended to 6-methylpterin (4) yielding with 11 and BF 3 small amounts of the N 1 - (21) and N 3 -riboside (14), with 7-methyl-pterin (5) the N 3 -riboside ( (15) in 6% yield and with 7-tert.butylpterin (8) again a mixture of N 1 - (24) and N 3 -riboside (18). A highly unpleasant reaction was encountered with pterin (1) itself which led after a tedious isolation and purification process only to 10% yield of the 1-(2,3,5.tri-O-benzoyl-ß-Dribofuranosyl)pterin (25). Debenzoylations of the sugar protecting groups can be achieved by the Zemplen 30 method as demonstrated with 13, 19 and 20, respectively, forming the free pterinnucleosides 28-30.…”