Solid phase synthesis of a metronidazole oligonucleotide conjugate.

Direct, solid phase synthesis of an oligonucleotide conjugate of the antibiotic drug metronidazole was accomplished by the phosphoramidite method. Removal of protecting groups and cleavage from the controlled pore glass (CPG) solid support was successful using mild conditions (20% Et(3)N in pyridine, then conc. NH(3) (aq) at rt for 30 min) whereas standard conditions (conc. NH(3) (aq) at 55 degrees C for 16 h) cleaved the drug.