(SR/RS)-Cyclohexanyl PNAs: Conformationally Preorganized PNA Analogues with Unprecedented Preference for Duplex Formation with RNA

Abstract
PNA oligomers H-GTAGATCAT-lys-NH2 with cis-(1S,2R/1R,2S)-cyclohexyl-T (III) in the backbone form PNA:RNA duplexes with Tm ∼30−50 °C higher than that of PNA:DNA duplexes. In comparison, cis-(1S,2R/1R,2S)-cyclopentyl PNA-T (IV) form highly stable duplexes with both RNA and DNA without discrimination.