The use of Hagemann's esters to prepare highly functionalized phenols and benzenes

Majetich, George; Allen, Scott D.

doi:10.3998/ark.5550190.0011.410

Cited by 7 publications

(6 citation statements)

References 3 publications

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“…Arenes of this type, possessing all- meta substitution patterns, would be challenging to synthesize through conventional aromatic substitution or cross-coupling approaches. Dehydrogenation reactions were accomplished using Pd/C as a catalyst without the need for an H 2 acceptor (products 38 – 42 ) . Dehydrogenation of the methylenecyclohexenes could also be carried out with SeO 2 but led to concomitant oxidation of the benzhydryl group to a benzophenone (products 44 and 45 ).…”

mentioning

confidence: 99%

Catalytic [5 + 1]-Cycloadditions of Vinylcyclopropanes and Vinylidenes

et al. 2020

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Polysubstituted cyclohexenes bearing 1,3 (meta) substitution patterns are challenging to access using the Diels–Alder reaction (the ortho–para rule). Here, we report a cobalt-catalyzed reductive [5 + 1]-cycloaddition between a vinylcyclopropane and a vinylidene to provide methylenecyclohexenes bearing all-meta relationships. Vinylidene equivalents are generated from 1,1-dichloroalkenes using Zn as a stoichiometric reductant. Experimental observations are consistent with a mechanism involving a cobaltacyclobutane formed from a [2 + 2]-cycloaddition between a cobalt vinylidene and a vinylcyclopropane.

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confidence: 99%

Catalytic [5 + 1]-Cycloadditions of Vinylcyclopropanes and Vinylidenes

et al. 2020

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“…Compound 7 was prepared by the reaction of 2 with TMSCN in the presence of molecular iodine followed by dehydration with trifluoroacetic acid (TFA). Aromatisation of the diene 7 was not possible using DDQ, 19 Pd (10%)/C 20 or CuBr 2 /LiBr. 21 However, reaction of 7 with selenium dioxide in 1,4-dioxane at reflux 22,23 produced the aromatic compound 8.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Novel Podocarpa-8,11,13-Triene-7- and 13-Nitriles and Evaluation of their Anti-Inflammatory and Cytotoxic Activity

Villamizar

Angarita

Blanco

et al. 2016

Journal of Chemical Research

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A series of novel podocarpa-8,11,13-triene-7- and 13-nitriles were prepared from the naturally occurring labdane diterpenoid (+)-manool, using podocarp-8(14)-en-13-one and 13-methoxypodocarpa-8,11,13-trien-7-one as key intermediates and TMSCN and acetonitrile as source of the nitrile. The synthesised compounds were screened for cytotoxicity against mouse macrophage cell line (RAW 264.7), human colon adenocarcinoma cell lines (HT-29) and human prostate adenocarcinoma cell lines (PC3) and for anti-inflammatory, as measured by the inhibition of nitric oxide (NO) production by RAW cells. 7-Oxopodocarpa-8,11,13-triene-13-nitrile exhibited significant inhibition of NO production (IC50 = 6 μM) and was not cytotoxic.

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“…[23] Of course, one could also dehydrogenate these Hagemann's ester derivatives to Nympheal (1) itself. [24] Experimental Section…”

Section: Discussionmentioning

confidence: 99%

“…These new insights should enable the design and synthesis of more renewable, biodegradable and non‐spermotoxic muguet odorants to accompany Lilybelle ( 12 ) and Biomuguet ( 13 ) in the sustainable future; the mixture 28a / 28b actually already could be such an addition to the perfumer's palette if ethyl acetoacetate ( 14 ) and isovaleraldehyde ( 22 ) are available from renewable resources [23] . Of course, one could also dehydrogenate these Hagemann ’s ester derivatives to Nympheal ( 1 ) itself [24] …”

Section: Introductionmentioning

confidence: 99%

On the Structure–Odor Correlation of Muguet Aldehydes: Synthesis of 3‐(4’‐Isobutyl‐2’‐methylphenyl)propanal (Nympheal) and Four Novel Derivatives from a Hagemann’s Ester

Kraft¹,

Ohrmann²,

Chandrasekaran³

et al. 2023

Helvetica Chimica Acta

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Lilybelle and Biomuguet are currently the only renewable and biodegradable non‐spermotoxic Lilial replacers. Being non‐aromatic, these lack however some of the green, aquatic aspects of Lilial that are present in the captive odorant Nympheal, 3‐(4‐isobutyl‐2‐methylphenyl)propanal, which is not available from renewable resources. Therefore, the influence of the aromatic nucleus on the odor of four new hydrogenated Nympheal derivatives was investigated, which were all accessible from the isobutyl Hagemann’s ester that was synthesized in 75 % yield from isovaleraldehyde with two equivalents of ethyl acetoacetate. The respective Hagemann’s ester was alkylated with 3‐bromopropanal dimethyl acetal and subjected to decarboxylative saponification, followed by hydride reduction and dehydration through the corresponding mesylate to furnish, after deprotection with formic acid, the corresponding exo‐ and endo‐dihydro‐Nympheal derivative. Full or partial hydrogenation of the central acetal‐protected intermediate provided after deprotection the analogous fully saturated analogue or the cyclohexene derivative. The olfactory properties of these four novel Nympheal derivatives are discussed and rationalized by computational olfactophore models.

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The use of Hagemann's esters to prepare highly functionalized phenols and benzenes

Cited by 7 publications

References 3 publications

Catalytic [5 + 1]-Cycloadditions of Vinylcyclopropanes and Vinylidenes

Catalytic [5 + 1]-Cycloadditions of Vinylcyclopropanes and Vinylidenes

Synthesis of Novel Podocarpa-8,11,13-Triene-7- and 13-Nitriles and Evaluation of their Anti-Inflammatory and Cytotoxic Activity

On the Structure–Odor Correlation of Muguet Aldehydes: Synthesis of 3‐(4’‐Isobutyl‐2’‐methylphenyl)propanal (Nympheal) and Four Novel Derivatives from a Hagemann’s Ester

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