Postsynthesis Functionalization of Oligonucleotides

Solid-phase oligodeoxynucleotide synthesis has become a routine procedure in most molecular-biology laboratories. The reagents for the synthesis of unmodified oligomers have been available for several years, and novel commercially available reagents that permit the introduction of useful analogs into DNA are offered with increasing frequency. Solid-phase RNA synthesis is also becoming accessible to the molecular-biology community. If a suitable protected derivative is available, solid-phase synthesis is usually the preferred method of incorporating a nonstandard residue into an oligomer. However, there are still situations in which it is advantageous, or even essential, to approach the synthesis of modified oligonucleotides in a different way, namely by derivatizing unprotected oligonucleotides or their analogs.