Nitration of <i>p</i>-<i>tert</i>-butyltoluene in acetic anhydride. 1,2 and 1,4 adducts

Fischer, Alfred; Röderer, Rolf

doi:10.1139/v76-568

Cited by 13 publications

(8 citation statements)

References 8 publications

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“…6-Acetoxy-3-tert-butyl-6-methylcyclohexa-2,4-dienone (3e). 5-tert-Butyl-2-methylphenol (1e 100 mg, 0.61 mmol) 49 was submitted to the DIB-mediated oxidative acetoxylation method we previously described 18 49 in MeOH was first performed according to the procedure A. The reaction mixture was then processed as described above, and the oily residue was purified by column chromatography, eluting with hexanes/Et 2 O (8:1), to furnish paraquinone 6 as colorless crystals (31 mg, 25%).…”

Section: General Procedures For Electrochemical Oxidation Procedures Amentioning

confidence: 99%

Iodane-mediated and electrochemical oxidative transformations of 2-methoxy- and 2-methylphenols

Quideau¹,

Pouységu²,

Deffieux³

et al. 2003

Arkivoc

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A series of 2-methoxy and 2-methylphenols have been submitted to oxygenative oxidation reactions using (1) the λ 3 -iodane DIB, (2) a non-explosive and non-moisture sensitive version of the λ 5 -iodane IBX, named SIBX for Stabilized IBX, and (3) anodic oxidation with the aim of identifying the best reaction conditions for preparing orthoquinonoid cyclohexadienone synthons. Both the use of DIB and anodic oxidation appeared equally valuable for making orthoquinone dimethyl ketals, but the λ 3 -and λ 5-iodane reagents are more appropriate to induce ortho-oxygenation of 2-methylphenols. In particular, SIBX emerged as a useful reagent for mediating ortho-hydroxylation into dimerizing orthoquinols, a tactic that can be applied to the synthesis of natural bis(monoterpenoids) such as aquaticol.

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Section: General Procedures For Electrochemical Oxidation Procedures Amentioning

confidence: 99%

Iodane-mediated and electrochemical oxidative transformations of 2-methoxy- and 2-methylphenols

Quideau¹,

Pouységu²,

Deffieux³

et al. 2003

Arkivoc

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“…In the series of p-alkyltoluenes (R = Me, Et, i-Pr, t-Bu)p-ethyltoluene is the only member which gives structurally isomeric 1,4-adducts as a consequence of nitration ipso to both 'For Part XXII, see ref. 2. alkyl groups (3)(4)(5).= Such structurally isomeric 1,4-adducts are particularly useful for the study of adduct reactions since they allow the elucidation of the regiospecificity of the reactions. In the earlier paper examples of two such reactions were reported (1).…”

mentioning

confidence: 99%

ipso Nitration. XXIII. Reactions of cyclohexadiene adducts from nitration of 4-ethyltoluene in acetic anhydride

Fischer¹,

Henderson²

1981

Can. J. Chem.

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. Can. J. Chem. 59,2314Chem. 59, (1981. The diastereoisomers of 4-ethyl-1-methyl-4-nitrocyclohexa-2,s-dienyl acetate (1) and 1-ethyl-4-methyl-4-nitrocyclohexa-2,sdienyl acetate (2) are stereospecifically reduced to the corresponding nitrocyclohexadienols with aluminum hydride. Each dienol is stereospecifically methylated to the corresponding methyl ether with methyl iodide, silver oxide, and potassium hydroxide. Acid-catalysed solvolysis of the acetates 1 and 2 results in the substitution of the acetate moiety by other nucleophiles and these reactions are not stereospecific. The products of rearomatization of dienyl acetates, dienols, and dienyl methyl ethers depend on the acidity and ionizing power of the solvents and are readily explained in terms of reactions involving a nitrocyclohexadienyl cation or acetoxy-(hydroxy-, methoxy-)cyclohexadienyl cation as key intermediates. In the 4-acetoxy-4-alkylcyclohexadienyl cation 1,2-migration of the acetoxyl group is more rapid than alkyl migration, but 1,2-alkyl migration is faster than migration ofthe hydroxyl or methoxyl groups in the corresponding cations. l-Ethyl-4-methoxy-4-methylcyclohexa-2,S-dien-l-ol and 4-ethyl-3-nitrotoluene are significant minor products in the solvolysis of l-ethyl-4-methyl-4-nitrocyclohexa-2,5-dien-l-ol in aqueous methanol. Nitration of p-ethyltoluene in the presence of sulfuric acid or in trifluoroacetic anhydride gives a mixture of 4-ethyl-2-nitro-and 4-ethyl-3-nitrotoluene in a 2: 1 ratio. on peut facilement expliquer la formation de divers produits sur la base de reactions impliquant, comme intermediaire cle, soit un cation nitrocyclohexadienyle ou un cation acCtoxy (hydroxy ou mtthoxy) cyclohexadiCnyle. Dans le cation acetoxy-4 alkyl-4 cyclohexadienyle, la migration-1,2 du groupe acetoxy est plus rapide que la migration alkyle, mais la migration-1,2 des groupes alkyles est plus rapide que la migration correspondante des groupes hydroxyle ou methoxyle. L'ethyl-1 mCthoxy-4 methyl-4 cyclohexadikne-2,s 01-1 et I'ethyl-4 nitro-3 tolukne sont des produits secondaires importants de la solvolyse de I'kthyl-1 methyl-4 nitro-4 cyclohexadiene-2,s 01-1 dans le methanol aqueux. La nitration du p-Cthyltoluene en presence d'acide sulfurique ou dans I

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“…In the case of diene 1 an X-ray crystal structure determination confirmed the structure assigned on the basis of the spectral data and gave the stereochemistry, the nitro and acetate groups being cis to each other (1). It seems reasonable to conclude that the 1,2 addition of acetyl nitrate, which is stereoselective in all of the substrates investigated and which is also stereoselective in the case of 4-tert-butyltoluene (12), is in all cases a syn addition. Shift reagent studies applied to the two members of a pair of diastereomeric adducts have been used to determine the stereochemistry of 1,4-adducts in which the acetate group is secondary (22), but the method could not be applied to the 1,2-dienes obtained in this work since a pure sample of the second diastereomer was not generally available.…”

Section: Structure and Spectra Of The Adductsmentioning

confidence: 81%