Reactivity in Cleavage of Dimethoxybenzenes by Sodium in Liquid Ammonia

Bunnett, J. F.; Jenvey, Judy

doi:10.1021/jo960148u

Cited by 11 publications

(9 citation statements)

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“…Treatment of 17 with lithium in liquid ammonia followed by tosylation afforded a mixture of the expected 3-aryl pyrrolidine 18 (28%) and 19 (36%), the product of a regioselective aryl ether reduction. This type of aromatic ether cleavage under reductive conditions has been documented for several 1,2-dialkoxybenzenes …”

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confidence: 62%

Double Reduction of Cyclic Aromatic Sulfonamides: A Novel Method for the Synthesis of 2- and 3-Aryl-Substituted Cyclic Amines

et al. 2004

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confidence: 62%

Double Reduction of Cyclic Aromatic Sulfonamides: A Novel Method for the Synthesis of 2- and 3-Aryl-Substituted Cyclic Amines

et al. 2004

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“…2-Methoxy-5-methylphenol (3). Following the above procedure with 3-hydroxy-4-methoxybenzaldehyde (isovanillin, 20.42 g, 134.22 mM), the crude product was recrystallized to provide 3 (16.67 g, 90% yield) as a colorless solid. Mp 33−34 °C (from hexanes); IR (film) 3507, 2937, 1275 cm -1 ; 1 H NMR (400 MHz, CDCl 3 ) δ 2.26 (s, 3H), 3.86 (s, 3H), 5.55 (br, 1H), 6.63−6.75 (m, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ 20.7, 56.0, 110.6, 115.4, 120.2, 131.1, 144.5, 145.4; MS (EI, 70 eV) m / z (rel intensity) 138 (M + , 85), 123 (100), 95 (27), 77 (16), 55 (15); HRMS (EI) calcd for C 8 H 10 O 2 (M + ) 138.0680, found 138.0689.…”

Section: Methodsmentioning

confidence: 99%

Intermolecular Diels−Alder Reactions of Brominated Masked o-Benzoquinones with Electron-Deficient Dienophiles. A Detour Method to Synthesize Bicyclo[2.2.2]octenones from 2-Methoxyphenols

et al. 2002

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Intermolecular Diels-Alder reactions of masked o-benzoquinones, i.e., 6,6-dimethoxy-2,4-cyclohexadienones 5-7 and 21-24 generated from 2-methoxyphenols 1-3 and 17-20, respectively, with electron-deficient dienophiles leading to highly functionalized bicyclo[2.2.2]octenones are described. The masked o-benzoquinones (MOBs) 5-7 underwent Diels-Alder cycloadditions with methyl acrylate, methyl methacrylate, and methyl vinyl ketone to provide bicyclo[2.2.2]octenones 13a-c to 15a-c (direct method) in low to moderate yields with the concomitant formation of considerable amounts of dimers 9-11. To retard dimerization and to improve the yields of the requisite bicyclo[2.2.2]octenones, a detour method comprised of sequential bromination of 2-methoxyphenols 1-4, oxidation and Diels-Alder reaction, and debromination has been developed. The oxidation of bromophenols 17-20 produced MOBs 21-24 which are stable enough to be isolated. The MOBs 21-24 underwent cycloaddition with electron-deficient dienophiles in a very efficient manner to afford the corresponding cycloadducts 25a-c to 28a-c in good to high yields without self-dimerization. When the cycloadducts 25a-c to 28a-c were treated with either Bu(3)SnH/AIBN or tributylammonium formate-palladium reagent, the corresponding debrominated products 13a-cto 16a-c were obtained in high to excellent yields. In general, the cycloadducts 13a-c to 15a-c were obtained in 20-40% higher yields via the detour method than those via the direct method. In both routes, the Diels-Alder reactions proceeded in a highly regio- and stereoselective manner to furnish a single cycloadduct in each case.

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“…These authors also give a current example of the use of sulfate esters as a protecting group in synthesis [7] as do Bunnett and Jenvey. [8]…”

Section: Other Recent Developmentsmentioning

confidence: 99%

The Elbs and Boyland-Sims peroxydisulfate oxidations

Behrman¹

2006

Beilstein J. Org. Chem.

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This paper reviews the recent literature on the title reactions and updates a 1988 review.Page 1 of (page number not for citation purposes) 10The Elbs and Boyland-Sims oxidations are shown in Scheme 1:Scheme 1: The Elbs and Boyland-Sims Oxidations.Both of these reactions, last reviewed in 1988 [1], are nucleophilic displacements on a peroxide oxygen of the peroxydisulfate ion. In the Elbs oxidation, the nucleophile is a phenolate anion (or a tautomer) and in the Boyland-Sims oxidation, it is a neutral aromatic amine. There is no radical involvement in either case (except in side reactions, see below). The products are aromatic sulfates whose orientation relative to the phenolic group is preferentially para in the Elbs oxidation and ortho in the Boyland-Sims case. These sulfates are useful in synthesis themselves or may be hydrolyzed in acid to the dihydric phenols (or aminophenols).The yields of products are typically low to moderate, but the simplicity of the reactions frequently recommends their use. Reactions are usually carried out by dissolving the phenol or amine in an alkaline aqueous medium, sometimes with the addition of a co-solvent such as pyridine, and then adding a peroxy- Page 2 of (page number not for citation purposes) 10 disulfate salt. The ammonium and sodium salts are much more soluble than the potassium salt. This low solubility may be used to advantage to ensure slow addition of the peroxydisulfate as it is established that higher yields are achieved when the phenol(amine)-peroxydisulfate ratio is large. Isolation of the product usually takes advantage of the high water solubility of the intermediate sulfate ester; acidification of the reaction mixture is followed by extraction of the unreacted starting material (in the case of phenols) by an appropriate organic solvent. The sulfate ester remains in the aqueous phase. Hydrolysis of the sulfate ester in aqueous acid produces the (usually) organic-soluble dihydric phenol. Reactions are usually run at room temperature or below to reduce the incursion of free radical reactions. The rates are rather slow with typical secondorder rate constants (at room temperature) in the range 0.1-20 L mol -1 min -1 .[1] Mechanisms of the reactionsThe mechanisms of both reactions have been clarified. In both cases this was done by synthesis of postulated intermediates. In the Boyland-Sims oxidation, the amine-O-sulfonate was the obvious choice that was supported by a number of kinetic studies. In the Elbs oxidation, since the product is preferentially the p-sulfate, the question was whether the initial attack was at the phenolate oxygen(3) followed by rearrangement to the p-sulfate(4) or whether the initial attack was by the tautomeric p-carbanion(5) (Scheme 3).Here it was possible to synthesize the first possibility by displacement of the fluoride ion from three dinitrofluorobenzenes by reaction with Caro's acid anion .[4] The key example was for 2,5-dinitrofluorobenzene(6) which offers both an ortho and a para position for the rearrangement. Fluoride 6...

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Reactivity in Cleavage of Dimethoxybenzenes by Sodium in Liquid Ammonia

Cited by 11 publications

References 31 publications

Double Reduction of Cyclic Aromatic Sulfonamides: A Novel Method for the Synthesis of 2- and 3-Aryl-Substituted Cyclic Amines

Double Reduction of Cyclic Aromatic Sulfonamides: A Novel Method for the Synthesis of 2- and 3-Aryl-Substituted Cyclic Amines

Intermolecular Diels−Alder Reactions of Brominated Masked o-Benzoquinones with Electron-Deficient Dienophiles. A Detour Method to Synthesize Bicyclo[2.2.2]octenones from 2-Methoxyphenols

The Elbs and Boyland-Sims peroxydisulfate oxidations

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