A ‘click chemistry’ approach to the efficient synthesis of modified nucleosides and oligonucleotides for PET imaging

Tritylation of alcohols under mild conditions without using silver salts

“…Using this method, tritylation of secondary alcohols can usually be achieved at ambient temperature within several hours. 2 In some cases higher temperature and longer reaction time were used, which were probably needed to achieve satisfactory yields. 3 Besides using silver salts, DMAP had been used to catalyze the reaction.…”

11C Click Chemistry Using [11C]Methyl Azide: Simplified, Versatile, and Practical Alternative Access to [11C]Nucleosides and [11C]Oligonucleotides for PET Imaging

“…[6] The methyl transfer was studied first on monomers 1c and deprotected 1b before studying it on 1d. Finally, and in contrast to Shirrmacher's work, who was forced to replace CuI by the copper sulfate/sodium ascorbate couple when applying his methodology to peptide labeling, our combination of Na + /15-crown-5/N 3 and CuI gave better results than with copper sulfate/sodium ascorbate (77 % yield in 2 min).…”

“…Having already reported work on the application of click chemistry in the labeling of nucleosides and oligonucleotides, [6,7] we naturally considered with interest the possibility of using [ 11 C]methyl azide as a click reactant for their 11 C labeling (Scheme 1). Indeed, the development of tracers for studying cell proliferation is a major area of research.…”

DNA Three Way Junction Core Decorated with Amino Acids-Like Residues-Synthesis and Characterization

“…The synthesis of the key (5′S)-5′-C-propargyl-thymidine phosphoramidite 9 started from the known 3′-O-tert-butyldiphenylsilyl-thymidine aldehyde 4 [22,23] that was reacted under Barbier′s conditions with propargyl bromide to provide a 3/7 diastereoisomeric mixture of (5′R)-5′-C and (5′S)-5′-C-propargyl-thymidine 5 and 6, respectively [24,25] (Scheme 1). The separation of the diastereoisomers required a tedious HPLC process to cleanly obtain the fast moving and major compound 6.…”