Multi-component reaction for the preparation of 1,5-disubstituted 1,2,3-triazoles by in-situ generation of azides and nickel-catalyzed azide-alkyne cycloaddition
An efficient one-pot procedure combining bromide conversion into azide followed by NiAAC for the preparation of 1,5-disubstituted 1,2,3-triazoles has been developed. This procedure prevents the use of isolated azides, which are insufficiently commercially available and could be potentially unstable and difficult to handle. Moreover, this one-pot method tolerates a broad range of functional moieties
1,4-Disubstituted-1H-1,2,3-triazoles 1 can easily be distinguished from the isomeric 1,5-disubstituted-1H-1,2,3-triazoles 2 by simple one-dimensional C-13 NMR spectroscopy using gated decoupling. The C-5 signal of 1 appears at delta similar to 120 ppm, while the C-4 signal of 2 appears at delta similar to 133 ppm. Computational studies also predict the upfield shift of C-5 of 1 relative to C-4 in 2.