(1S,2R/1R,2S)-aminocyclohexyl glycyl thymine PNA:: Synthesis, monomer crystal structures, and DNA/RNA hybridization studies

graphic The synthesis of ethyl cis-(1S,2R/1R,2S)-2-aminocyclohex-1-yl-N-(thymin-1-yl-acetyl) glycinate (10a and 10b) via enzymatic resolution of the key racemic intermediate trans-2-azido cyclohexanols 3 is reported. The crystal structures of 10 show equatorial disposition of the tertiary amide group, with the torsion angle beta in the range 60-70degrees. The PNA oligomers incorporating these show differential effects in hybridizing with complementary DNA and RNA.