Patent 7169916 was granted and assigned to Ionis Pharmaceuticals on January, 2007 by the United States Patent and Trademark Office.
A process of manufacturing oligonucleotides includes a 5′-deblocking step in which the 5-blocking group is removed with dichloroacetic acid that is essentially free of chloral. The process is useful for making oligonucleotides that are substantially free of chloral adducts.