1,4-Migration of a nitro-group in the rearomatization of 4,5-dimethyl-2,4-dinitrocyclohexa-2,5-dienyl acetate

Fischer, Alfred; Iyer, Lokanathan M.

doi:10.1039/c39790001096

Cited by 3 publications

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“…The mechanism shown in Scheme 3 involving consecutive SN2' processes accounts for the apparent 1,4 migration of the nitro group (2). In the first step a general nucleophile adds at the 3 position of lam, allylic to the acetate group which simultaneously departs as an anion.…”

Section: Reactions With Nucleophilesmentioning

confidence: 99%

ipso Nitration. XXVI. Nitration of 1,2-dimethyl-4-nitrobenzene. Formation and reactions of adducts

Fischer¹,

Henderson²,

Iyer³

1985

Can. J. Chem.

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. Nitration of 1,2-dimethyl-4-nitrobenzene in a mixture of acetic anhydride and trifluoroacetic anhydride gives the diastereoisomers of 4,5-dimethyl-2,4-dinitrocyclohexa-2,5-die acetate (50%), in addition to the 1,2-dimethyldinitrobenzenes. In moderate and more strongly acid conditions the adduct gives 4-nitro-, 3,4-dinitro-, and 3,5-dinitro-o-xylene. In neutral and weakly acid solutions 4-nitro-and 3,5-dinitro-o-xylene are formed by a radical and a sigmatropic pathway. ' The adduct reacts facilely with nucleophiles by allylic substitution to give a 5,6-dimethyl-6-nitrocyclohexa-2,4-dienyl derivative which, in many instances, undergoes a second allylic substitution to a new 4,5-dimethyl-2,4-dinitrocyclohexa-2,5-die derivative. Depending on the nature of the introduced substituent, these 2,4-and 2,5-dienyl products may eliminate nitrous acid, under the reaction conditions, to give the corresponding aromatic compound. The dienyl acetates undergo acid-catalysed transesterification to the corresponding dienols. ALFRED FISCHER, GEORGE N. HENDERSON et LOKANATHAN M. IYER. Can. J. Chem. 63, 2390Chem. 63, (1985. La nitration du dimtthyl-1,2 nitro-4 benzkne dans un mtlange d'anhydride acCtique et d'anhydride trifluoroacCtique conduit, en plus des dimtthyl-1,2 dinitrobenzknes, a la formation des diasttrtoisomkres de I'acktate du dirnkthyl-4,5 dinitro-2,4 cyclohexadikne-2,5 yle (50%). Dans des milieux modtrtment et plus forternent acides, I'adduit conduit aux nitro-4, dinitro-3,4 et dinitro-3,5 o-xylknes. Dans des milieux neutre ou Itgkrement acide, les nitro-4 et dinitro-3,5 o-xylknes se foment par un mtcanisme radicalaire suivi d'une transposition sigmatropique. Par substitution allylique, I'adduit rtagit facilement avec les nucltophiles et il conduit un dtrivt dimtthyl-5,6 nitro-o cyclohexadikne-2,4 yle qui, dans plusieurs cas, subit une deuxikme substitution allylique pour conduire i un nouveau dtrivt dirntthyl-4,5 dinitro-2,4 cyclohexadikne-2,5 yle. Dtpendant de la nature des substituants introduits, ces produits dikne-2,4 (ou -2,5) yles peuvent Climiner de I'acide nitreux dans les conditions de la rkaction &in de conduire i la formation du compost aromatique correspondant. Les acttates de dienyles subissent des transesttrifications acido-catalystes conduisant aux ditnols correspondants.[Traduit par le journal]Nitration at a substituted position, ipso nitration (3), is competitive with nitration at an unsubstituted position in many aromatic compounds. The resulting ipso-nitrocyclohexadienyl cation is captured as a relatively stable acetate ester in acetic anhydride and can be isolated. In previous work the adduct from 3,4-dimethybenzonitrile has been obtained (4). The nitro group has directing and deactivating effects similar to those of the cyano group and it was anticipated that nitration of 1,2-dimethyl-4-nitrobenzene (4-nitro-o-xylene) would occur at the 2 position, ipso to methyl, to form an adduct. Results and discussion4-Nitro-o-xylene did not react at all when it was treated with nitric acid (5 mol ratio) in ...

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Section: Reactions With Nucleophilesmentioning

confidence: 99%

ipso Nitration. XXVI. Nitration of 1,2-dimethyl-4-nitrobenzene. Formation and reactions of adducts

Fischer¹,

Henderson²,

Iyer³

1985

Can. J. Chem.

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Formation of Carbon–Halogen Bonds (Cl,Br,I)

Sasson

2009

Patai's Chemistry of Functional Groups

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Introduction Halogenation in Presence of Solid Supports or Catalysts Halogen Exchange and Transhalogenation Reactions Oxyhalogenations Cohalogenation and Mixed Halogenation Halogen–Halogen Reagents Carbon–Halogen Reagents Nitrogen–Halogen and Phosphorus–Halogen Reagents Oxygen–Halogen Reagents Sulfur–Halogen Reagents Silicon–Halogen Reagents Halogenation with Metal Halides and Halodemetallation Halogenation in Special Environments Carbon–Halogen Bond Formation by Extrusion of CO , CO 2 or SO 2 Ring Opening of Oxiranes

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ChemInform Abstract: 1,4‐MIGRATION OF A NITRO‐GROUP IN THE REAROMATIZATION OF 4,5‐DIMETHYL‐2,4‐DINITROCYCLOHEXA‐2,5‐DIENYL ACETATE

Fischer¹,

Iyer²

1980

Chemischer Informationsdienst

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1,4-Migration of a nitro-group in the rearomatization of 4,5-dimethyl-2,4-dinitrocyclohexa-2,5-dienyl acetate

Cited by 3 publications

References 0 publications

ipso Nitration. XXVI. Nitration of 1,2-dimethyl-4-nitrobenzene. Formation and reactions of adducts

ipso Nitration. XXVI. Nitration of 1,2-dimethyl-4-nitrobenzene. Formation and reactions of adducts

Formation of Carbon–Halogen Bonds (Cl,Br,I)

ChemInform Abstract: 1,4‐MIGRATION OF A NITRO‐GROUP IN THE REAROMATIZATION OF 4,5‐DIMETHYL‐2,4‐DINITROCYCLOHEXA‐2,5‐DIENYL ACETATE

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