Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Dinucleoside phosphotriester

Much more advanced and effective appeared to be the method reported recently by Beaucage et al. [127]. Starting from ( )-2-amino-l-phenylethanol (88) the authors performed chemoselective N-acylation with ethyl fluoroacetate (89) providing 90, followed by its reaction with hexaethylphosphorous triamide (Scheme 23). Cyclic N-acylphosphoramidite 91 has been obtained as a mixture of diastereomeric rotamers. Condensation of AT4-benzoyl-5 -0-DMT-2 -deoxy-cytidine 92 with 91 in the presence of lH-tetrazole gave, after silica gel chromatography, pure Rc,RP-93 and Sc,SP-93.31P NMR studies indicated that when Rp-93 or Sp-93 was reacted with 3 -0-acetyl-AT-benzoylcytidine (94) and A ATjN jN -tetramethylguanidine (TMG), the dinucleoside phosphotriester was formed in nearly quantitative yield with full P-stereospecificity. After subsequent sulfurization, the P-stereodefined dinucleoside phosphorothioate tri-... [Pg.195]

Using phosphotriester methods, dinucleoside (3 - 50-monophosphates containing 6-methyl-2,-deoxyuridine at the 3 - or 5 -end have been prepared.44 N.m.r. spectroscopy indicates that this nucleoside possesses the syn conformation in these compounds, and, on treatment with snake venom phosphodiesterase, d(m6UpT) is degraded, while d(Apm6U) is not, indicating that this enzyme, a 3 -exonuclease, requires the anti conformation to be present in the substrate. Two modified nucleo-side-5 -monophosphates, (20) and (21), which are resistant to 5 -nucleotidase, have been isolated from tRNA snake venom hydrolysates.45 A synthesis of (20) has been reported.46... [Pg.158]

In the 1,3,2-dioxaphosphole method a bis(2-butene-2,3-diyl) pyrophosphate is used as the condensing agent. It allows two successive esterifications of one phosphate group to be performed without additional activation. First a 5 -O-protected nucleoside is added in methylene chloride in the second reaction an unprotected nucleoside can be used, since only the 3 OH group is able to attack the cyclic enediol 3 -nucleosidyl phosphotriester. Protected dinucleoside triesters are obtained in 80% yield. Removals of protective groups, methoxytrityl by means of trifluoroacetic acid in methylene chloride and 1-methylacetonyl by aqueous triethyl-amine, also give about 80% yield (F. Ramirez, 1975, 1977). [Pg.219]

Treatment of methoxyphosphorodichloridite with li/-1,2,4-triazole in THF at —78 °C affords methoxyphosphorobis(triazolidite) which reacts with 5 -0-dimethoxytrityl-2 -deoxynucIeosides to give (24), which in turn affords (25) and (26) on treatment with excess A -trimethylsilyl-dimethylamine or -morpholine, respectively. This preparation of deoxynucleoside phosphoramidites avoids the use of chlorodialkyl aminomethoxyphosphines, which are unstable and difficult to prepare. Little or no 3 -3 dinucleoside phosphite is formed in this case, although if the methyl group is replaced by 2-chlorophenyl, some 3 -3 -linked by-product is found. Species of type (24)—(26) are of central importance in the phosphite method of oligonucleotide phosphotriester synthesis. [Pg.163]

Miller, P. S, Fang, K. N., Konda, N. S., and Ts o, P. O. P (1971) Syntheses and properties of adenine and thymine nucleoside alkyl phosphotriesters, the neutral analogs of dinucleoside monophosphates. J. Am. Chem. Soc. 93,6657-6665. Laster, B H., Schinazi, R. F., Fairchild, R. G, Popenoe, E. A, and Sylvester, B (1985) Neutron Capture Therapy, Proc. 2nd Int Sym. (pub. 1986), 46-54. Kobayashi, T and Konda, K. (1984) Boron-10 dosage in cell nucleus for neutron capture therapy—Boron selective dose ratio Proceeding of the First International Symposium on Neutron Capture Therapy, October 12-14,1983, BNL Report No. 51730, pp. 120-127. [Pg.244]

Cosstick, R. and Williams, D. M. (1987) An approach to the stereoselective synthesis of Sp-dinucleoside phosphorothioates using phosphotriester chemistry. Nucl. Acids Res. 15,9921-9943. [Pg.311]


See other pages where Dinucleoside phosphotriester is mentioned: [Pg.136]    [Pg.265]    [Pg.215]    [Pg.136]    [Pg.265]    [Pg.215]    [Pg.219]    [Pg.155]    [Pg.19]    [Pg.585]    [Pg.194]    [Pg.216]    [Pg.170]    [Pg.164]    [Pg.530]    [Pg.208]    [Pg.209]    [Pg.215]    [Pg.248]    [Pg.94]    [Pg.332]    [Pg.630]    [Pg.340]    [Pg.250]    [Pg.250]    [Pg.42]    [Pg.410]   
See also in sourсe #XX -- [ Pg.215 ]




SEARCH



Dinucleoside

Phosphotriesters

© 2024 chempedia.info