Photochemistry of Substituted Benzoylformate Esters. A Convenient Method for the Photochemical Oxidation of Alcohols

Pirrung, Michael C.; Tepper, Ronald J.

doi:10.1021/jo00113a029

Cited by 37 publications

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“…A first straightforward pathway to synthesize 3‐benzoylmenadiones 1 was investigated by using a silver(I)‐catalyzed decarboxylation reaction between menadione and α‐ketoaromatic acids 5 according to the reaction shown in Scheme . To do so, starting α‐keto acids 5 a and 5 a′ had to be prepared, first, by a described method and were obtained in 80 and 98 % yield, respectively. When the Kochi–Anderson reaction conditions were applied to menadione and α‐ketoaromatic acids 5 , an acyl radical was generated, producing directly the 3‐benzoylmenadione derivatives 1 a and 1 a′ in 45 % and 41 % yield, respectively (Scheme ).…”

Section: Resultsmentioning

confidence: 99%

A Mild and Versatile Friedel–Crafts Methodology for the Diversity‐Oriented Synthesis of Redox‐Active 3‐Benzoylmenadiones with Tunable Redox Potentials

Cotos¹,

Donzel²,

Elhabiri³

et al. 2020

Chemistry A European J

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A series of highly diversified 3‐aroylmenadiones was prepared by a new Friedel–Crafts acylation variant/oxidative demethylation strategy. A mild and versatile acylation was performed between 1,4‐dimethoxy‐2‐methylnaphthalene and various activated/deactivated benzoic and heteroaromatic carboxylic acids, in the presence of mixed trifluoroacetic anhydride and triflic acid, at room temperature and in air. The 1,4‐dimethoxy‐2‐methylnaphthalene‐derived benzophenones were isolated in high yield, and submitted to oxidative demethylation with cerium ammonium nitrate to produce 3‐benzoylmenadiones. All 1,4‐naphthoquinone derivatives were investigated as redox‐active electrophores by cyclic voltammetry. The electrochemical data recorded for 3‐acylated menadiones are characterized by a second redox process, the potentials of which cover a wide range of values (500 mV). These data emphasize the ability of the generated structural diversity at the 3‐aroyl chain of these electrophores to fine‐tune their corresponding redox potentials. These properties are of significance in the context of antimalarial drug development and understanding of the mechanism of bioactivation/action.

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Section: Resultsmentioning

confidence: 99%

A Mild and Versatile Friedel–Crafts Methodology for the Diversity‐Oriented Synthesis of Redox‐Active 3‐Benzoylmenadiones with Tunable Redox Potentials

Cotos¹,

Donzel²,

Elhabiri³

et al. 2020

Chemistry A European J

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“…2a (720 mg, 6.60 mmol) and p-methoxybenzoylformic acid 3b 23 (1.19 g, 6.60 mmol) were added consecutively to a solution of acetone semicarbazone 1a (760 mg, 6.60 mmol) in methanol (10 mL) and stirred for 3 days, and the resulting solid was filtered to give compound 4b (1.28 g, 48%) as colorless crystals (MeOH-CH 2 Cl 2 , 1:6), mp 246-247°C; 1 H NMR (400 MHz, DMSO-d 6 …”

Section: N-cyclohexyl-2-[n′-carbamoyl-n-(2-oxo-2-{p-methoxy}-phenylacmentioning

confidence: 99%

“…Benzylisocyanide 2b (780 mg, 6.66 mmol) and p-methoxybenzoylformic acid 3b 23 (1.20 g, 6.66 mmol) were added consecutively to a solution of cyclohexanone semicarbazone 1b (1.034 mg, 6.66 mmol) in methanol (10 mL) and stirred for 3 days, and the resulting solid was filtered to give compound 4e (1.69 g, 56%) as colorless crystals 8, 173.1, 169.3, 164.90, 160.0, 140.0, 132.5, 129.0, 128.2, 127.5, 125.4, 114.8, 68.3, 56.37, 43.3, 32.3, 30.0, 25.4, 22.4, 22. 6.24;N,12.38. Found: C,63.57;H,6.35;N,12.24.…”

Section: N-cyclohexyl-1-[n′-carbamoyl-n-(2-oxo-2-{p-methoxyphenyl}-acmentioning

confidence: 99%

“…N-Cyclohexyl-1-[N′-carbamoyl-N-(2-oxo-2-phenylacetyl)hydrazino]cyclohexanecarboxamide 4c. Cyclohexylisocyanide 2a (900 mg, 8.24 mmol) and benzoylformic acid 3a (1.237 g, 8.24 mmol) were added consecutively to a solution of cyclohexanone semicarbazone 1b (1.279 g, 8.24 mmol) in methanol (15 mL) and stirred for 3 days, and the resulting solid was filtered to give compound 4c (1.88 g, 55%) as colorless crystals (MeOH-CH 2 -Cl 2 , 1:6), mp 243-244°C; 1 H NMR (400 MHz, DMSO-d 6 ) δ 9.46 (s, 1H), 9.26 (s, 1H), 7.86 (d, 2H, J ) 7.5 Hz), 7.73 (d, 1H, J ) 7.5 Hz), 7.57 (t, 2H, J ) 7.5 Hz), 6.19 (br s, 2H), 3.65 (m, 1H), 2.34 (m, 1H), 1.77 (m, 9H), 1.40 (m, 10H); 13 C NMR (100 MHz, DMSO-d 6 ) δ 191.2, 171.7, 168.9, 160.0, 135.5, 132.6, 129.9, 129.5, 68.3, 47.5, 32.9, 32.3, 30.0, 26.2, 25.4, 24.4, 22.4, 22.3; IR (KBr) Ṽ 3384 and 3248 (NH), 3085, 2930, 2853, 1697, 1685, 1656 and 1650 (CdO), 1225 cm -1 ; EIMS m/z 309 (M + -105, 8), 271 (15), 260 (42), 156 (25), 105 (100), 77(23). Anal.…”

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confidence: 99%

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Synthesis of 3-Hydroxy-6-oxo[1,2,4]triazin-1-yl Alaninamides, a New Class of Cyclic Dipeptidyl Ureas

et al. 2006

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Cyclohexyl or benzyl isocyanide, benzoyl-, or 4-methoxybenzoylformic acid and semicarbazones underwent Ugi reactions in methanol for 3 days to give the Ugi adducts, which were then stirred with sodium ethoxide in ethanol for 12 h to give 3-hydroxy-6-oxo[1,2,4]triazin-1-yl alaninamides. The X-ray diffraction structure of the first example showed the tautomer having the proton in the O2 atom that was fixed in the crystal by packing in dimers with a H-bond distance of 1.9 A. Selected [1,2,4]triazines were treated with diazomethane for 12 h to get the O-methyl derivatives. Both hydroxy and O-methyl derivatives obtained by this method constitute a new class of pseudopeptidic [1,2,4]triazines composed of two different amino acids, arylglycine and alanine derivatives, in which the N-terminal arylglycine and the peptidic amide nitrogen atoms are bonded through a urea moiety.

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“…So far, only a few authors have reported the influence of O 2 on the mechanism of the photoirradiation of a-keto esters [5] [10] [11] [16] [17]. Pirrung and Tepper, for example, proposed a mechanism invoking the formation of a 1,3,4-trioxane intermediate resulting from the reaction of molecular O 2 with the previously formed 1,4-diradical [10]. Alternatively the formation of a hydroperoxide as a possible intermediate was described by Hu and Neckers [16].…”

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confidence: 99%

Controlled Release of Perfumery Aldehydes and Ketones by Norrish Type-II Photofragmentation of -Keto Esters in Undegassed Solution

Rochat

Minardi

Laumer

et al. 2000

HCA

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Alkyl or aryl a-keto esters of primary or secondary alcohols decompose upon irradiation at 350 ± 370 nm from the intermediate triplet state into aldehydes or ketones in polar, as well as apolar solvents. The use of these keto esters as delivery systems for the controlled release of perfumery aldehydes and ketones was investigated by photoirradiation in the presence of oxygen with a Xe or UV lamp, as well as outdoor sunlight. Systematic GC/ MS analysis of the irradiated solutions showed that, under these conditions, the desired Norrish type-II fragmentation of the ester side chain is the predominant reaction pathway in most of the cases. g-H Abstraction from the alkyl side chain of alkyl keto esters, as well as an intramolecular PaternoÁ-Büchi reaction or epoxidation of the alkene function in different citronellyl a-keto esters were identified as the most important side reactions. Some of the experimental findings have been rationalized on the basis of ab initio and density-functional calculations. (Cyclohexyl)oxoacetates and oxo(phenyl)acetates were found to be the most suitable precursors for the desired perfumery applications.1. Introduction. ± Aldehydes and ketones are important classes of fragrances that are present in all kinds of perfumes. However, many of them are very volatile and can, after application, only be perceived over a relatively short period of time. Furthermore, as constituents of perfumes for a variety of different bodycare or household applications, such as shampoos, soaps, all purpose cleaners, fabric softeners, or detergent powders, they are often too hydrophilic and thus easily carried away by water during various rinsing processes instead of staying on substrates like hair, skin, or fabrics.To prolong the desired odor perception of this class of compounds, we have prepared a series of photolabile, hydrophobic, non-volatile fragrance precursors as potential delivery systems for the controlled release of perfumery aldehydes and ketones in typical bodycare and household applications. In this publication, we describe the fragrance release from a-keto esters upon irradiation with artificial light sources, as well as natural sunlight in the presence of O 2 [1]. Some interesting fragrances for release in functional perfumery are depicted in Fig. 1 [2].The photolysis of alkyl or aryl a-keto esters of primary or secondary alcohols has been intensively studied since the early sixties [3 ± 7]. It was found that these esters decompose from their intermediate triplet state into aldehydes or ketones upon irradiation at 350 ± 370 nm in polar, as well as apolar solvents [7 ± 11]. Most of the photoirradiations described in the literature were carried out in degassed solutions in the absence of O 2 . The relatively good yields of the fragmentation process have allowed the use of a-keto esters as intermediates for the transformation of primary or secondary alcohols to aldehydes and ketones, respectively [12].

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Photochemistry of Substituted Benzoylformate Esters. A Convenient Method for the Photochemical Oxidation of Alcohols

Cited by 37 publications

References 0 publications

A Mild and Versatile Friedel–Crafts Methodology for the Diversity‐Oriented Synthesis of Redox‐Active 3‐Benzoylmenadiones with Tunable Redox Potentials

A Mild and Versatile Friedel–Crafts Methodology for the Diversity‐Oriented Synthesis of Redox‐Active 3‐Benzoylmenadiones with Tunable Redox Potentials

Synthesis of 3-Hydroxy-6-oxo[1,2,4]triazin-1-yl Alaninamides, a New Class of Cyclic Dipeptidyl Ureas

Controlled Release of Perfumery Aldehydes and Ketones by Norrish Type-II Photofragmentation of -Keto Esters in Undegassed Solution

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