Oxidative [3+2]-annulation of nitroalkenes and azolium ylides in the presence of Cu(II): efficient synthesis of [5,5]-annulated N-fused heterocycles

12 November 2021, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


A facile synthesis of [5,5]-annulated N-fused heterocycles – pyrrolo[2,1-b]thiazoles and pyrrolo[1,2-b]indazoles via Cu(II)-mediated oxidative [3+2]-annulation between nitroalkenes and azolium ylides was developed. The reaction proceeds in mild conditions with copper (II) trifluoroacetate/2,6-lutidine system as a promoter. The method is applicable to a broad range of nitroalkenes and azolium salts, providing target N-fused heterocycles in moderate to good yields. In the case of α-fluoronitroalkenes unique fluorinated derivatives were accessed via this methodology.


N-fused heterocycles
Oxidative reactions
Copper-mediated reactions

Supplementary materials

Supporting information for paper
Synthesis of initial compounds (nitroalkenes and azolium salts), and copies of NMR spectra.


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