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

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.

Synthetic Approaches to Crinipellin Based Tetraquinanes via Ring‐Rearrangement Metathesis and Ring‐Closing Metathesis

“…Here, the formation of diquinane 11 was inevitable due to the unfavourable disposition of adjacent olefinic moieties in its precursor 3 b . Further, this observation is in line with recent reports [22b,28] …”

“…Therefore, we considered various options for metathesis between dissimilar unsaturated side chains ( A – C ) of 3 b to generate the ring‐closure products 16 and 17 (Figure 8a). However, based on the above results, it was clear that the ring‐closure between A & B and A′ & B′ is not feasible due to the trans disposition of adjacent olefinic moieties [22b,28] . In this context, it is worth mentioning that among cis ‐, and trans ‐isomers of bicyclo[3.3.0]octane (Figure 8b), trans ‐isomer is 6.4 kcal/mol more strained than the cis ‐isomer [29] .…”

A Modular Approach to Angularly Fused Polyquinanes via Ring-Rearrangement Metathesis: Synthetic Access to Cameroonanol Analogues and the Basic Core of Subergorgic Acid and Crinipellin

“…The formation of a mixture of products is due to different metathetic behavior of olefinic moieties A – F that are present in the RRM precursor 65 (Figure ). The metathesis between B and C , C and D , and D and F is not feasible due to unfavorable ring-junction stereochemistry and/or trans disposition of these olefinic moieties . Metathesis of the remaining terminal double bonds A and F , C and E , D and E , and E and F is feasible to produce the corresponding RRM products 18 , 19 , 52 , and 66 – 68 .…”

Crystal structure of [1,3-bis(2,4,6-trimethylphenyl)imidazolidin-2-ylidene]dichlorido(2-{[(2-methoxyethyl)(methyl)amino]methyl}benzylidene)ruthenium

“…The list of such areas includes production of bioactive substances with a desired selectivity of the resulting double bond, obtaining highly functionalized organic compounds, and the synthesis of new materials including polymers (Pederson et al, 2002;Kozłowska et al, 2014;Eivgi et al, 2020). Complexes including a six-membered chelate ruthenium ring are effective catalysts for various types of olefin metathesis reactions (Polyanskii et al, 2019a,b;Kumandin et al, 2020Kumandin et al, , 2023Antonova et al, 2020;Vasilyev et al, 2023). On the other hand, the catalytic activity of metal complexes is dictated by the ligands, while the coordination environment of the metal center and ligands can be decorated by attaching different non-covalent bond donor or acceptor substituents for the regulation of the structure and the reactivity of the catalysts (Gurbanov et al, 2022a,b;Mahmoudi et al, 2017a,b;Mahmudov et al, 2013Mahmudov et al, , 2023.…”