N-acylphosphoramidites and their use in oligonucleotide synthesis

摘要

The invention provides a method of thermally deprotecting the internucleosidic phosphorus linkage of an oligonucleotide, which method comprises heating in a fluid medium at a substantially neutral pH. The preferred protecting group is of the formula: wherein R1 is H, R1a, OR1a, SR1a or NR1aR1a', wherein R1a and R1a' independently represent H, alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or aralkyl substituents. Alternatively, NR1aR1a' represents a heterocycle. X is O or S. Z is O, S, NR2a, CR2aR2a' or CR2aR2a'CR2bR2b' wherein R2a, R2a', R2b and R2b' independently represent H, alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or aralkyl substituents. Alternatively, R1a or R1a', in combination with any of R2a, R2a', R2b or R2b', together with C=X can comprise a ring. R2, R2', R3 and R3' each represent H, alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or aralkyl substituents. Alternatively, R2 or R2', in combination with R3 or R3', together with the carbons to which they are bonded, comprise a benzo-fused bicyclic ring. The foregoing substituents can be unsubstituted or substituted. The present invention further provides a method of synthesizing an oligonucleotide using the thermal deprotection method described above, and novel oligonucleotides and intermediates that incorporate the thermolabile protecting group used in accordance with the present invention.