STUDIES ON STERIC AND ELECTRONIC CONTROL OF 2'-3'-PHOSPHORYL MIGRATION IN 2'-PHOSPHORYLATED URIDINE DERIVATIVES AND ITS APPLICATION TO THE SYNTHESIS OF 2'-PHOSPHORYLATED OLIGOURIDYLATES
M. Sekine et al., STUDIES ON STERIC AND ELECTRONIC CONTROL OF 2'-3'-PHOSPHORYL MIGRATION IN 2'-PHOSPHORYLATED URIDINE DERIVATIVES AND ITS APPLICATION TO THE SYNTHESIS OF 2'-PHOSPHORYLATED OLIGOURIDYLATES, Journal of organic chemistry, 61(12), 1996, pp. 4087-4100
For the synthesis of 2'-phosphorylated oligouridylates by use of new p
hosphoramidite building units, several masked phosphoryl groups have b
een examined as 2'-phosphate precursors, which should not be migrated
to the 3' position when the 3' hydroxy protecting group must be remove
d to introduce a phosphoramidite residue into the 3'-position. As a co
nsequence, bis(2-cyano-1,l-dimethylethoxy)thiophosphoryl (BCMETP) was
found to be the most suitable 2'-phosphate precursor. This thiophospho
ryl group could be introduced into the 2'-hydroxyl of 3',5'-silylated
uridine derivative 7 by phosphitylation with 2-cyano-1,l-dimethylethox
y)(diethylamino)phosphine followed by sulfurization. Treatment of the
2'-thiophosphorylated product 15 with (HF)(x) . Py in THF gave exclusi
vely the 3',5'-unprotected uridine derivative 16a. Compound 16a was co
nverted to the phosphoramidite unit 22 via a two-step reaction. This b
uilding block was used for the solution phase synthesis of U(2'-p)pU (
29) and U(2'-ps)pU (30). Both the 2-cyano-1,1-dimethylethyl and 2-cyan
oethyl groups were effectively removed from the fully protected deriva
tive 25 by treatment with DBU in the presence of N,O-bis(trimethylsily
l)acetamide (BSA). The resulting 2'-thiophosphoryl group was successfu
lly converted to a phosphoryl group by iodine treatment to give U(2'-p
)PU (29). U(2'-ps)pU (30) was also synthesized by a modified procedure
without the iodine treatment. Reaction of 29 with a new biotinylating
reagent in aqueous solution in the presence of MgCl2 gave a biotin-la
beled product 35 having a pyrophosphate bridge at the 2' position. Rea
ction of 30 with monobromobimane gave the 2'-S-alkylated product 33 in
aqueous solution. Application of the phosphoramidite unit 22 to the s
olid phase synthesis using aminopropyl CPG gel gave successfully [U(2'
-p)p]U-n (n = 1, 3, 5). It was found that stability of the succinate l
inker between the CPG and oligouridylates was unaffected by the treatm
ent with DBU when BSA was present. Several enzymatic properties of the
synthetic 2'-phosphorylated and 2'-thiophosphorylated oligouridylates
are also described.