Copper-free Click Chemistry

At Glen Research, our goal was to offer a copper-free click phosphoramidite reagent with the following properties:

• Simple to use

• Stable in solution on the synthesizer

• Stable to ammonium hydroxide and AMA

• Excellent click performance in 17 hours or less at room temperature

From the variety of cyclooctyne-based copper-free click reagents so far described, we have chosen to offer compounds based on a dibenzo-cyclooctyne (DBCO) structure.  We are offering 5’-DBCO-TEG Phosphoramidite for preparing oligos with a 5’-DBCO modification and DBCO-dT-CE Phosphoramidite for inserting a DBCO group at any position within the oligonucleotide. In addition, we offer a further DBCO phosphoramidite – DBCO-Serinol Phosphoramidite.  Using our proprietary serinol backbone as a non-nucleosidic spacer allows the DBCO group to be placed at any location within a sequence with multiple additions clearly possible. DBCO-sulfo-NHS Ester is also offered for post-synthesis conjugation reactions.  DBCO-modified oligos may be conjugated with azides in organic solvents, such as DMSO, or aqeous buffers. Depending on the azide used, the reaction will go to completion in 4-17 hours at room temperature.  Simple desalting on a Glen Gel-Pak™ leads to a product with virtually quantitative conjugation efficiency.

Note: We now recommend that synthesis of oligos containing DBCO-dT be completed using 0.5 M CSO in anhydrous acetonitrile (40-4632-xx).  Acceptable results can be achieved with iodine oxidation if DBCO-dT is subjected to no more than 8-10 cycles.