Application of New Efficient Hoveyda-Grubbs Catalysts Comprising an N→Ru Coordinate Bond in a Six-Membered Ring for the Synthesis of Natural Product-Like Cyclopenta[ b]furo[2,3- c]pyrroles

Molecules. 2020 Nov 17;25(22):5379. doi: 10.3390/molecules25225379.

Abstract

The ring rearrangement metathesis (RRM) of a trans-cis diastereomer mixture of methyl 3-allyl-3a,6-epoxyisoindole-7-carboxylates derived from cheap, accessible and renewable furan-based precursors in the presence of a new class of Hoveyda-Grubbs-type catalysts, comprising an N→Ru coordinate bond in a six-membered ring, results in the difficult-to-obtain natural product-like cyclopenta[b]furo[2,3-c]pyrroles. In this process, only one diastereomer with a trans-arrangement of the 3-allyl fragment relative to the 3a,6-epoxy bridge enters into the rearrangement, while the cis-isomers polymerize almost completely under the same conditions. The tested catalysts are active in the temperature range from 60 to 120 °C at a concentration of 0.5 mol % and provide better yields of the target tricycles compared to the most popular commercially available second-generation Hoveyda-Grubbs catalyst. The diastereoselectivity of the intramolecular Diels-Alder reaction furan (IMDAF) reaction between starting 1-(furan-2-yl)but-3-en-1-amines and maleic anhydride, leading to 3a,6-epoxyisoindole-7-carboxylates, was studied as well.

Keywords: 3-allyl-3a,6-epoxyisoindoles; Hoveyda–Grubbs catalysts; IMDAF reaction; cyclopenta[b]furo[2,3-c]pyrroles; furan; nitrogen–ruthenium coordinate bond; ring-rearrangement metathesis.

MeSH terms

  • Biological Products / chemical synthesis*
  • Biological Products / chemistry
  • Catalysis
  • Crystallography, X-Ray
  • Magnetic Resonance Spectroscopy
  • Molecular Conformation
  • Pyrroles / chemistry*
  • Ruthenium / chemistry*
  • Solvents / chemistry
  • Stereoisomerism
  • Temperature

Substances

  • Biological Products
  • Pyrroles
  • Solvents
  • Ruthenium