Use of phthaloyl protecting group for the automated synthesis of 3'-[(hydroxypropyl)amino] and 3'-[(hydroxypropyl)triglycyl] oligonucleotide conjugates.
The chemical stability of oligonucleotides (ODNs) containing 3'-propanolamine was investigated. Invariably, all the ODNs synthesized from Fmoc-protected 3-aminopropane-1,2-diol-CPG support gave a mixture of three compounds at the end of automated synthesis as analyzed by denaturing PAGE and HPLC. On the basis of analytical procedures, these compounds were identified to be 3'-[N-acetyl-N-(hydroxypropyl)amino],3'-[(hydroxypropyl)amino], and 3'-hydroxyl ODNs. The instability of the amino protecting group under the synthesis conditions was responsible for this observed heterogeneity. In order to evaluate the stability, a comparative study on the chemical stability of the ODN containing amino-protecting groups such as [(9-fluorenylmethyl)oxy]carbonyl (Fmoc), trifluoroacetyl (TFA), and phthaloyl was undertaken. The results indicate that the phthaloyl group provided the best stability for the synthesis of 3' amine-modified ODNs, and the protecting group is cleaved and deprotected in concentrated ammonium hydroxide:40% aqueous methylamine, 1:1, for 5-10 min, at 56 degrees C. The 3'-hydroxypropyl)triglycyl] ODN conjugates were also synthesized from Fmoc- and phthaloyl-protected (hydroxypropyl)triglycine-CPG supports.
Vu
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Triplex Pharmaceutical Corporation, Woodlands, Texas 77380, USA.
Joyce
N
N
Rieger
M
M
Walker
D
D
Goldknopf
I
I
Hill
T S
TS
Jayaraman
K
K
Mulvey
D
D
D001483:Base Sequence; D004355:Drug Stability; D005449:Fluorenes / Q000138:chemical synthesis / Q000737:chemistry; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis* / Q000737:chemistry*; D010795:Phthalic Acids / Q000138:chemical synthesis / Q000737:chemistry; D011412:Propanolamines / Q000138:chemical synthesis / Q000737:chemistry
D005449:Fluorenes; D009838:Oligodeoxyribonucleotides; D010795:Phthalic Acids; D011412:Propanolamines