The 3-(N-tert-butylcarboxamido)-1-propyl group as an attractive phosphate/thiophosphate protecting group for solid-phase oligodeoxyribonucleotide synthesis.
Among the various phosphate/thiophosphate protecting groups suitable for solid-phase oligonucleotide synthesis, the 3-(N-tert-butylcarboxamido)-1-propyl group is one of the most convenient, as it can be readily removed, as needed, under thermolytic conditions at neutral pH. The deprotection reaction proceeds rapidly (t(1/2) approximately 100 s) through an intramolecular cyclodeesterification reaction involving the amide function and the release of the phosphate/thiophosphate group as a 2-(tert-butylimino)tetrahydrofuran salt. Incorporation of the 3-(N-tert-butylcarboxamido)-1-propyl group into the deoxyribonucleoside phosphoramidites 1a-d is achieved using inexpensive raw materials. The coupling efficiency of 1a-d in the solid-phase synthesis of d(ATCCGTAGCTAAGGTCATGC) and its phosphorothioate analogue is comparable to that of commercial 2-cyanoethyl deoxyribonucleoside phosphoramidites. These oligonucleotides were phosphate/thiophosphate-deprotected within 30 min upon heating at 90 degrees C in Phosphate-Buffered Saline (PBS buffer, pH 7.2). Since no detectable nucleobase modification or significant phosphorothioate desulfurization occurs, the 3-(N-tert-butylcarboxamido)-1-propyl group represents an attractive alternative to the 2-cyanoethyl group toward the large-scale preparation of therapeutic oligonucleotides.
Division of Therapeutic Proteins, Center for Biologics Evaluation and Research, Food and Drug Administration, 8800 Rockville Pike, Bethesda, Maryland 20892, USA.
Andrzej
A
Wilk
Marcin K
MK
Chmielewski
Andrzej
A
Grajkowski
Lawrence R
LR
Phillips
Serge L
SL
Beaucage
D001483:Base Sequence; D002384:Catalysis; D002625:Chemistry, Organic / Q000379:methods*; D004591:Electrophoresis, Polyacrylamide Gel; D008401:Gas Chromatography-Mass Spectrometry; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis* / Q000737:chemistry*; D009943:Organophosphorus Compounds / Q000737:chemistry*
D009838:Oligodeoxyribonucleotides; D009943:Organophosphorus Compounds