Cb. Reese et Pz. Zhang, PHOSPHOTRIESTER APPROACH TO THE SYNTHESIS OF OLIGONUCLEOTIDES - A REAPPRAISAL, Journal of the Chemical Society. Perkin transactions. I, (19), 1993, pp. 2291-2301
The phosphotriester approach to the synthesis of oligodeoxyribo- and o
ligoribo-nucleotides in solution has been reinvestigated. The efficacy
of mesitylene-2-sulfonyl chloride (MSCl) 15a, 2,4,6-triisopropylbenze
nesulfonyl chloride (TrisCl) 15b, 4-bromobenzenesulfonyl chloride 15c,
naphthalene-1-sulfonyl chloride 39, and 2- and 4-nitrobenzenesulfonyl
chlorides 40a and 40b, respectively, as activating agents has been ex
amined. The latter arenesulfonyl chlorides have been used in conjuncti
on with the following nucleophilic catalysts: 1-methylimidazole, 3-nit
ro-1H-1,2,4-triazole 19, 5-(3-nitrophenyl)-1H-tetrazole 20a, 5-(3,5-di
nitrophenyl)-1H-tetrazole 20b, 5-(1-methylimidazol-2-yl)-1H-tetrazole
21, 5-[(1-methylimidazol-2-yl)methyl]-1H-tetrazole 22, 4-ethoxypyridin
e 1-oxide 14a,4,6-dinitro-1-hydroxybenzotriazole 29a, 1-hydroxy-4-nitr
o-6-(trifluoromethyl)benzotriazole 29b, 1-hydroxy-5-phenyltetrazole 30
a and 1-hydroxy-5-(3-nitrophenyl)tetrazole 30b. The rates of formation
and yields of the fully protected dideoxyribonucleoside and diribonuc
leoside phosphates 37 and 47, respectively, were determined using vari
ous combinations of activating agents and nucleophilic catalysts. Alth
ough 2- and 4-nitrobenzenesulfonyl chlorides 40a and 40b, respectively
, proved to be the most powerful activating agents, their use in the d
eoxy-series led to the formation of by-products and hence to unsatisfa
ctory isolated yields of the dideoxyribonucleoside phosphate 37.