Synthesis of new, base-modified PNA monomers.
A number of N-Boc-protected peptide nucleic acids (PNA) monomers containing 5-aryl- and 5-alkynyl-uracil bases have been synthesized using different palladium-catalyzed cross-coupling reactions. Starting from the base-unprotected 5-iodo-uracil PNA monomer, only the Stille couplings were accomplished successfully, while Suzuki couplings with boronic acids containing the same aryl groups failed. During Sonogashira couplings with terminal alkynes, significant amounts of unrequired furano[2,3-d]pyrimidine by-products were formed. Protection of the lactam function by p-methoxybenzylation prevented the opportunity for intramolecular cyclization as well as formation of a negative charge on the 4-O atom, making it possible to reach almost quantitative yields at Sonogashira couplings and acceptable conversions in Suzuki reactions.
Sipos
Ferenc
F
Institute of Biomolecular Chemistry, Chemical Research Center of the Hungarian Academy of Sciences, Budapest, Hungary.
Sági
Gyula
G
D008956:Models, Chemical; D020135:Peptide Nucleic Acids / Q000138:chemical synthesis* / Q000737:chemistry; D014498:Uracil / Q000737:chemistry
D020135:Peptide Nucleic Acids; D014498:Uracil