- Reductive heterocyclizations via indium-iodine-promoted conversion of 2-nitroaryl imines or 2-nitroarenes to 2,3-diaryl-substituted indazoles
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While N-(2-nitrobenzylidene)anilines produced mixtures of 2,1-benzisoxazoles and 3-anilino-2-aryl-2H-indazoles in the presence of indium and iodine in MeOH, N-(2-nitrobenzylidene)anilines were transformed into 3-anilino-2-aryl-2H-indazoles as the predominant major product through the change of the solvent from protic MeOH to aprotic THF. In an indium-mediated one-pot reductive reaction, 2-benzaldehydes and anilines in THF were also successfully transformed into the corresponding indazoles. This journal is The Royal Society of Chemistry.
- Ahn, Gil Hwan,Lee, Jung June,Jun, Young Moo,Lee, Byung Min,Kim, Byeong Hyo
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- The Rearrangement of Aromatic Compounds. Part 3. The Mechanism of Rearrangement of Nitrated Hydrocarbons in Trifluoromethanesulphonic Acid
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1,3-Dialkyl-2-nitrobenzenes (C6H3R2NO2; R = Me, Et, and Pri) rearrange in trifluoromethanesulphonic acid to the corresponding 4-nitro derivatives; with R = Et, this reaction is accompanied by dehydration to 7-ethyl-3-methylanthranil.The reaction rate increases markedly with the size of the alkyl group; with R = Me, the reaction was studied at 110 deg C but, with R = Pri, temperatures of 36-54 deg C were used.The studies with R = Me show the reaction to be first-order with the rate coefficients (k1) increasing rapidly with the acidity of the solution 1)/d(-H0)> = 1.45, decreasing with acidity to o.49.Double-labelling experiments with 1H and 15N show the reaction to be intramolecular. 1,2,4-Trimethyl-3-nitrobenzene also rearranges under these conditions to give mainly the 5-nitro isomer.The above results are discussed in terms of a direct 1,3-shift of the nitro group.
- Bullen, John V.,Ridd, John H.,Sabek, Omaima
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p. 1681 - 1685
(2007/10/02)
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- THE CYCLISATION AND REARRANGEMENT OF THE NITRO DERIVATIVES OF AROMATIC HYDROCARBONS IN TRIFLUOROMETHANESULPHONIC ACID
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A number of the nitro derivatives of aromatic hydrocarbons undergo reactions in trifluoromethanesulphonic acid at ca. 100 deg C in which either the nitro group undergoes a 1,3-rearrangement or cyclisation occurs to form an anthranil.The rates and product composition have been determined for reactions in which the subsituents ortho to the nitro group are methyl or ethyl.For the rearrangement reaction to occur, it appears necessary that the nitro group should be initially between two alkyl substituents.The cyclisation reaction is significant only when one of the ortho-substituents is an ethyl group.
- Bullen, John V.,Ridd, John H.,Sabek, Omaima
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p. 291 - 296
(2007/10/02)
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