Resin backbone peak suppression

Broad signals from the poly(styrene) resin backbone can interfere with interesting substrate signals.

Use of a modified CPMG NMR pulse sequence can attenuate (but usually not completely remove) the broadest signals in the spectrum corresponding to the resin backbone. The caveat that needs to be considered that naturally broad substrate signals will also suffer such attenuation.

In the illustrated example the ¹H spectra were recorded to follow the loading of a radical cyclisation precursor onto a PS resin support. The resin subsequently underwent a radical cyclisation with Bu₃SnH affording product in good yield following cleavage from the support.

Data Collection

Bruker DPX400/2 FT-NMR spectrometer (legacy)

4 mm HR-MAS probe