An N-vinylation of imidazole and benzimidazole with a paramagnetic vinyl bromide was investigated. Among the tested procedures, Pd-catalyzed reaction was the most powerful one. The N-vinylation of 2-aminobenzimidazole with a β-bromo-α,β-unsaturated pyrroline nitroxide aldehyde offered 1,1,3,3-tetramethyl-1H-benzimidazo[1,2-a]pyrrolo[3,4-e]pyrimidin-2(3H)-yloxyl radical and the corresponding non-cyclized Schiff base. The reaction of a β-bromo-α,β-unsaturated pyrroline nitroxide aldehyde with imidazole gave β-imidazo-α,β-unsaturated pyrroline nitroxide aldehyde, which was reduced to the alcohol and converted to an unstable allyl chloride.

Reactions of β‐bromo‐β,γ‐unsaturated pyrroline nitroxide aldehyde (1) or nitrile (4) or their diamagnetic forms (5, 6) with 2‐aminothiophenol or 2‐mercaptobenzimidazole were evaluated. The reaction could be reproduced more easily with the application of O‐acetyl derivatives of nitroxides to generate 2‐substituted‐benzothiazole, pyrrolo[3,4‐b]benzo[1,5]tiazepine scaffolds with 2‐aminothiophenol and benzimidazo[2,1‐b]pyrrolo[3,4‐e]‐[1,3]thiazine scaffold with 2‐mercaptobenzimidazole.

A series of new 3-substituted-4-iodo-(2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-1-yl)oxidanyl compounds is synthesized to achieve NH2- and SH-specific spin labels. The new vinyl iodides are tested in Sonogashira and Buchwald–Hartwig cross-coupling reactions to produce a paramagnetic β-amino acid ester, pyrroline nitroxide-condensed­ heterocycles, including a paramagnetic α,α′-dipyridyl ligand and a spin-labeled sulfonamide.