Ring-opening carbonyl–olefin metathesis of norbornenes

Abstract

<p>A computational and experimental study of the hydrazine-catalyzed ring-opening carbonyl-olefinmetathesis of norbornenes is described. Detailed theoretical investigation of the energetic landscapefor the full reaction pathway with six different hydrazines revealed...</p>

Carbonyl–Olefin Metathesis

“…In 2020, Lambert and co-workers expanded the concept of hydrazine-catalyzed ring-opening carbonyl–olefin metathesis reactions of aldehydes to include norbornenes (Scheme ), using a combined approach of catalyst design and computational analysis . The major challenge confronting a shift to a significantly less-strained substrate like norbornene is that the [3 + 2]-cycloreversion becomes both endergonic and the rate-determining step of the catalytic cycle.…”

“…Interestingly, the corresponding ketone substrates also prove reactive under the optimal reaction conditions; however, the low yields observed with these substrates point to complications in the condensation or cycloaddition steps due to steric strain. Lambert and co-workers were also able to provide additional mechanistic support for the hypothesis of sequential [3 + 2]- and retro-[3 + 2]-cycloadditions − with the crystallization of cycloadduct 289 . The configuration of 289 was confirmed by X-ray crystallographic analysis.…”

“…Of particular importance was the finding that other strained olefins, such as cyclobutenes and cyclopentenes, were likely to have significantly higher activation barriers for the key In 2020, Lambert and co-workers expanded the concept of hydrazine-catalyzed ring-opening carbonyl−olefin metathesis reactions of aldehydes to include norbornenes (Scheme 45), using a combined approach of catalyst design and computational analysis. 90 The major challenge confronting a shift to a significantly less-strained substrate like norbornene is that the [3 + 2]-cycloreversion becomes both endergonic and the ratedetermining step of the catalytic cycle. To identify a hydrazine that would enable a viable catalytic process with such substrates, a virtual screen of catalysts was conducted.…”

Brønsted Acid-Catalyzed Carbonyl–Olefin Metathesis: Synthesis of Phenanthrenes via Phosphomolybdic Acid as a Catalyst

“…In recent years, the catalytic version of this method had begun to emerge and it greatly improved the atom and step economy of the reaction . To date, significant advances have been achieved in the catalytic carbonyl–olefin metathesis (CCOM), and organocatalysts, a few traditional Lewis acids, organo-Lewis acids, and Lewis acidic superelectrophiles have been successfully discovered (Scheme A). In addition, with a more robust reaction design, for instance, the strategy of obtaining 1,3-diols through the photoinduced hole-catalyzed formation followed by Grob fragmentation has been formulated, which considerably enriched the synthetic arsenal of modern chemists …”

Polycyclic heteroaromatics via hydrazine-catalyzed ring-closing carbonyl–olefin metathesis

“…Using 5 mol% of the hydrazine salt 10 furnished the RCCOM product 8 in 67% yield after 15 h at 80 °C in a sealed vial with THF as a solvent (entry 1). The [2.2.2]-bicyclic hydrazine 20 salt 11 was also productive (entry 2), albeit somewhat less so. Notably, iron( iii ) chloride generated no conversion at either ambient or elevated temperatures (entries 3 and 4).…”