Fig. 1: Challenges in catalytic intermolecular [5 + 1] benzannulation development by using cyclopropene and isocyanide as a substrate pair.
From: NHC-Ni(II)-catalyzed cyclopropene-isocyanide [5 + 1] benzannulation
![Fig. 1: Challenges in catalytic intermolecular [5 + 1] benzannulation development by using cyclopropene and isocyanide as a substrate pair.](http://media.springernature.com/full/springer-static/image/art%3A10.1038%2Fs41467-022-31896-y/MediaObjects/41467_2022_31896_Fig1_HTML.png?as=webp)
a Transition-metal mediated two-steps alkene-isocyanide insertion strategy. b Pd(II)-catalyzed cyclopropene polymerization, and the dimerization product structure. c Transition-metal catalyzed cyclopropene rearrangement to indene derivatives and subsequent dimerization. d Semmelhack/Wulff 1,4-hydroquinones synthesis. e Ni-catalyzed isocyanide polymerization. f Isocyanide insertion to Ni(II)R bonds for carbonyl derivatives preparation. g Nucleophilic insertion on Ni(II) isocyanide complex. h Isocyanide as a ligand in Pd-catalyzed metalloid insertion to cyclopropenes. i (NHC)Ni(II) catalyzed [5 + 1] benzannulation by cyclopropene and isocyanide.
