3 years ago

Mechanism and Origins of the Chemo- and Regioselectivities in Nickel-Catalyzed Intermolecular Cycloadditions of Benzocyclobutenones with 1,3-Dienes

Mechanism and Origins of the Chemo- and Regioselectivities in Nickel-Catalyzed Intermolecular Cycloadditions of Benzocyclobutenones with 1,3-Dienes
Genping Huang, Zhong-Liang Wang, Hongyan Zou
The nickel-catalyzed intermolecular cycloadditions of benzocyclobutenones with 1,3-dienes developed by Martin and co-workers are featured with the exclusive proximal C−C bond cleavage and a high chemoselectivity of the [4+4] over the [4+2] cycloaddition. In this report, the detailed reaction mechanism and the origins of the selectivities were investigated by means of density functional theory calculations. The results show that the reaction is initiated by a C−C oxidative addition of the benzocyclobutenone to form the five-membered nickelacycles. A subsequent exo 1,4-insertion/C−C reductive elimination and an endo 1,4-insertion/C−C reductive elimination lead to the [4+4] and [4+2] cycloaddition products, respectively. The 1,4-insertion of the 1,3-diene into the Ni−C bond was calculated to be the rate- and selectivity-determining step of the reaction. The calculations reproduced quite well the experimentally observed exclusive proximal C−C bond cleavage and the high chemoselectivity of the [4+4] over the [4+2] cycloaddition. In particular, it was found that the steric repulsion between the phosphine ligand and the α-substituent of the benzocyclobutenone has a dramatic impact on the 1,4-insertion, which enables the experimentally observed selectivities. Different ways: DFT calculations were performed to investigate the nickel-catalyzed intermolecular cycloadditions of benzocyclobutenones with 1,3-dienes (see scheme). The steric repulsion between the phosphine ligand and the α-substituent of the benzocyclobutenone has a dramatic impact on the 1,4-insertion, which enables the observed exclusive proximal C−C bond cleavage and the high chemoselectivity for the [4+4] cycloaddition.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/chem.201702316

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.