TY - JOUR
T1 - Aromatization of enamines promoted by a stoichiometric amount of palladium(II) salts
T2 - A novel method for the synthesis of aromatic amines
AU - Ishikawa, T.
AU - Uedo, E.
AU - Tani, R.
AU - Saito, S.
PY - 2001/1/12
Y1 - 2001/1/12
N2 - Enamines (1a-r) prepared from cyclohexanones, cyclohexane-1,3-diones, or tetralones led to arylamines (2a-r) in one pot when treated with a stoichiometric amount of palladium salts [PdCl2-(MeCN)2] in acetonitrile in the presence of triethylamine at room temperature or at elevated temperature, in some cases for 5 min to 2 h. The initial electrophilic attack of palladium chloride on the β-carbon of the enamines led to a σ-palladium species (8) which triggered a series of reactions (→ 9 → 19 → 11 → 12) destined for aromatization to give 2a-r in good yields. The intervention of such a σ-palladium species has been attested by a trapping experiment. On the basis of this reaction mechanism, we have developed another new process capable of transforming acyclic compounds having 6-en-2-one frameworks (16, 23, 25) to arylamines (2s-u) when their enamines were treated under the similar conditions as above, featuring again the formation of σ-palladium species such as 8 as the initial key intermediate.
AB - Enamines (1a-r) prepared from cyclohexanones, cyclohexane-1,3-diones, or tetralones led to arylamines (2a-r) in one pot when treated with a stoichiometric amount of palladium salts [PdCl2-(MeCN)2] in acetonitrile in the presence of triethylamine at room temperature or at elevated temperature, in some cases for 5 min to 2 h. The initial electrophilic attack of palladium chloride on the β-carbon of the enamines led to a σ-palladium species (8) which triggered a series of reactions (→ 9 → 19 → 11 → 12) destined for aromatization to give 2a-r in good yields. The intervention of such a σ-palladium species has been attested by a trapping experiment. On the basis of this reaction mechanism, we have developed another new process capable of transforming acyclic compounds having 6-en-2-one frameworks (16, 23, 25) to arylamines (2s-u) when their enamines were treated under the similar conditions as above, featuring again the formation of σ-palladium species such as 8 as the initial key intermediate.
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U2 - 10.1021/jo001331x
DO - 10.1021/jo001331x
M3 - Article
C2 - 11429898
AN - SCOPUS:0035847202
VL - 66
SP - 186
EP - 191
JO - Journal of Organic Chemistry
JF - Journal of Organic Chemistry
SN - 0022-3263
IS - 1
ER -