Synthesis of nucleoside and nucleotide conjugates of bile acids, and polymerase construction of bile acid-functionalized DNA.
Aqueous Sonogashira cross-coupling reactions of 5-iodopyrimidine or 7-iodo-7-deazaadenine nucleosides with bile acid-derived terminal acetylenes linked via an ester or amide tether gave the corresponding bile acid–nucleoside conjugates. Analogous reactions of halogenated nucleoside triphosphates gave directly bile acid-modified dNTPs. Enzymatic incorporation of these modified nucleotides to DNA was successfully performed using Phusion polymerase for primer extension. One of the dNTPs (dCTP bearing cholic acid) was also efficient for PCR amplification.
Direct determination of tautomerism in purine derivatives by low-temperature NMR spectroscopy
An investigation of the purine derivatives N,N-dimethyl-N'-(7(9)-H-purin-6-yl)-formamidine, 6-chloropurine and 6-methoxy purine at low temperatures by NMR spectroscopy has been carried out. Low temperature enabled us in two cases to detect the separate NMR signals of N7-H and N9-H tautomers.