摘要 |
A method for preparing an oligonucleotide comprising the steps of a) providing a hydroxyl containing compound having the formula (A), wherein B is a heterocyclic base and i) R<sub>2</sub> is H, a protected 2'-hydroxyl group, F, a protected amino group, an O-alkyl group, an O-substituted alkyl, a substituted alkylamino or a C4 '-O2 ' methylen linkage; R<sub>3</sub> is OR'<sub>3</sub>, NHR"<sub>3</sub>, NR"<sub>3</sub>R'<sub>3</sub>, wherein R<sub>3</sub> is a hydroxyl protecting group, a protected nucleotide or a protected oligonucleotide, R"<sub>3</sub>, R"<sub>3</sub> are independently amine protecting groups, and R<sub>5</sub> is OH or ii) R<sub>2</sub> is H, a protected 2'-hydroxyl group, F, a protected amino group, an O-alkyl group, an O-substituted alkyl, a substituted alkylamino or a C4'-O2 'methylen linkage; R<sub>3</sub> is OH and R<sub>5</sub> is OR'<sub>5</sub> and R'<sub>5</sub> is a hydroxyl protecting group, a protected nucleotide or a protected oligonucleotide or iii) R<sub>2</sub> is OH, R<sub>3</sub> is OR'<sub>3</sub>, NHR"<sub>3</sub>, NR"<sub>3</sub>R'"<sub>3</sub>, wherein R<sub>3</sub> is a hydroxyl protecting group, a protected nucleotide or a protected oligonucleotide, R"<sub>3</sub>, R"<sub>3</sub> are independently amine protecting groups, and R<sub>5</sub> is OR'<sub>5</sub> and R'<sub>5</sub> is a hydroxyl protecting group, a protected nucleotide or a protected oligonucleotide b) reacting said compound with a phosphitylating agent in the presence of an activator having the formula (I) (activator I) wherein R = alkyl, cycloalkyl, aryl, aralkyl, heteroalkyl, heteroaryl; R<sub>1</sub>, R<sub>2</sub> = either H or form a 5 to 6-membered ring together; X<sub>1</sub>, X<sub>2</sub> = independently either N or CH; Y = H or Si(R<sub>4</sub>)<sub>3</sub>, with R<sub>4</sub>= alkyl, cycloalkyl, aryl, aralkyl, heteroalkyl, heteroaryl; B = deprotonated acid to prepare a phosphitylated compound; c) reacting said phosphitylated compound without isolation with a second compound having the formula (A) wherein R<sub>5</sub>, R<sub>3</sub>, R<sub>2</sub>, B are independently selected, but have the same definition as above in the presence of an activator II different from activator I. |