Application of “click chemistry” to 5-bromo-2’-deoxyuridine (Br-dU)

5-Bromo-2'-deoxyuridine is a synthetic analog of thymidine which can be incorporated into DNA during the S-phase of the cell cycle. It can be used for the study of cell kinetics and pathological analysis by means of immunohistochemistry and fluorescent labeling.

We are striving to develop a reaction sequence for the fluorescent labeling of Br-dU that includes the Suzuki-Miyaura cross-coupling^[1] reaction and "click chemistry"^[2]. The "click reaction" is a copper(I) catalyzed 1,3-dipolar cycloaddition reaction between a terminal alkyne and an azide. Our Suzuki-Miyaura reaction with Br-dU is conducted with an arylboronic acid, containing a terminal alkyne group or can be further functionalized with this moiety. Prior to an application to isolates of DNA from Br-dU incubated cells, we are currently synthesizing and characterizing various intermediates of this reaction sequence. This includes conversion into a phosphoramidite (PA) of Br-dU and the Suzuki-Miyaura reaction product before "click coupling" to an azido functionalized dye. Further work will include PA incorporation into DNA and comparison of products from the reaction sequence on Br-dU containing DNA.