Oligonucleotides containing 7-propynyl-7-deazaguanine: synthesis and base pair stability

Oligonucleotides incorporating the propynyl derivative of 7-deaza-2′-deoxyguanosine () were synthesized by solid-phase oligonucleotide synthesis. As building blocks the phosphoramidites were prepared. The incorporation of into oligonucleotides exerts a positive effect on the DNA duplex stability. The duplex stabilization by was higher than that of 7-iodo-7-deaza-2′-deoxyguanosine (). The stabilizing effect of the 7-propynyl group introduced in the 7-deazapurines is similar to that reported for 8-aza-7-deazapurines. From CD spectra it was deduced that the B-DNA structure is not significantly altered by compound .