Formation of substituted benzofuranones-2 by a Nenitzescu reaction

Mikerova, N. I.; Panisheva, E. K.

doi:10.1007/bf00472202

Cited by 3 publications

(3 citation statements)

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“…Next to varying reaction conditions, a control experiment with hydroquinone instead of methyl-p-benzoquinone was performed using one equivalent hydroquinone and 0.1 equivalent zinc triflate in DCM at 40 °C . As expected, no conversion was observed after 22 h. Mikerova et al, which showed that sterically demanding enamino hydroquinones readily cyclize to benzofuranone derivatives in acidic medium [46,47]. Aside from this two-step synthesis via isolated enamino hydroquinones [46,47], benzofuranones have rarely been described as products from the Nenitzescu reaction.…”

Section: Resultsmentioning

confidence: 84%

“…Presumably, this heterocycle is formed via the acid-catalyzed lactonization of hydroquinone intermediate I12 (Scheme 5). This hypothesis is substantiated by the studies of Panisheva et al and Mikerova et al, which showed that sterically demanding enamino hydroquinones readily cyclize to benzofuranone derivatives in acidic medium [46,47]. Aside from this two-step synthesis via isolated enamino hydroquinones [46,47], benzofuranones have rarely been described as products from the Nenitzescu reaction.…”

Section: Resultsmentioning

confidence: 96%

“…This hypothesis is substantiated by the studies of Panisheva et al and Mikerova et al, which showed that sterically demanding enamino hydroquinones readily cyclize to benzofuranone derivatives in acidic medium [46,47]. Aside from this two-step synthesis via isolated enamino hydroquinones [46,47], benzofuranones have rarely been described as products from the Nenitzescu reaction. Sung et al reported the formation of benzofuranones via the Blaise-Nenitzescu reaction, which occurs by the condensation of an in situ-generated zinc complexed enaminoester and a quinone [48].…”

Section: Resultsmentioning

confidence: 96%

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Exploration of the Divergent Outcomes for the Nenitzescu Reaction of Piperazinone Enaminoesters

et al. 2023

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The Nenitzescu reaction is a condensation reaction between an enamine and a quinone, which can give rise to a wide variety of reaction products depending on the nature of the starting material and the reaction conditions. The most commonly observed products are 5-hydroxyindoles and 5-hydroxybenzofurans. Both classes are of interest since they are known to possess a variety of promising bioactivities. Despite the high chemodivergency for this reaction, it remains an interesting synthetic strategy thanks to the mild reaction conditions, easily accessible starting materials and simple reaction procedures. For these reasons, our research group investigated the Nenitzescu reaction of piperazinone enaminoesters, resulting in the unexpected formation of rearranged 2-imidazolidinone benzofurans. In this work, we aimed to develop reaction conditions that favor the formation of 5-hydroxyindoles via an extensive, multivariate optimization study. This led to valuable insights into the parameters that influence regio- and chemoselectivity. Furthermore, two novel products were obtained, a pyrrolo[2,3-f]indole and a benzofuranone, both of which are rarely reported in the literature.

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