Synthesis of an oxyamino-containing phenanthroline derivative for the efficient preparation of phenanthroline oligonucleotide oxime conjugates

A phenanthroline derivative bearing an oxyamino linker was efficiently prepared from commercial 5-nitro-1,10-phenanthroline. The subsequent reaction with an oligonucleotide containing an aldehyde either at the 5′ end or the 3′ end afforded, in good yield, the phenanthroline–oligonucleotide conjugates through oxime bond formation.