Structures of dimers and trimers of 1-trimethylacetylindole produced in presence of aluminum chloride

Formation of an Unusual Dimeric Compound by Lead Tetraacetate Oxidation of a Corynanthe-Type Indole Alkaloid, Mitragynine.

“…This fact would support our mechanistic consideration described above. Quite recently, the production of the dimers and trimers of 1-trimethylacetylindole in the presence of aluminum chloride was reported, 28) in which nucleophilicity of the benzene part (C-6) in the indole ring under the particular condition was proposed. An interesting dimerization of the simple indole derivatives with anodic oxidation is also reported.…”

Triflic Acid as an Efficient Brønsted Acid Promoter for the Umpolung of N‐Ac Indoles in Hydroarylation Reactions

“…N-Acetyl-3-(4-methoxyphenyl)-3,6-dimethylindoline (3 y) TfOH: 3 y was also prepared from 1-acetyl-3,6-dimethylindole 1 o (94 mg, 0.5 mmol), anisole 2 b (120 mL, 1.10 mmol) as electron-rich arene and TfOH (110 mL 1.25 mmol) in 500 mL of CH 2 Cl 2 following General Procedure A. Preparative TLC purification (Petroleum ether/EtOAc: 8/2) led to 3 y as a brown oil (139 mg, 0.471 mmol, 94%). 6,158.4,142.5,139.2,138.2,137.0,127.6 (2C),124.9,123.5,117.8,113.9 (2C),66.4,55.4,47.1,27.4,24.3,21.8;IR (NaCl), n (cm À1 ): 2963,2931,2835,1663,1608,1511,1398,1250,1183,1031,832,812 N-Acetyl-3-(4-methoxyphenyl)-3-methyl-6-fluoroindoline (3 z) TfOH: 3 z was prepared from 1-acetyl-3-methyl-6-fluoroindole 1 p (95 mg, 0.497 mmol), anisole 2 b (120 mL, 1.10 mmol) as electron-rich arene and TfOH (110 mL 1.25 mmol) in 0.5 mL of CH 2 Cl 2 following General Procedure A. Preparative TLC purification (Petroleum ether/EtOAc: 8/2) led to 3 z brown oil (139 mg, 0.464 mmol, 93%).…”

“…[1][2][3][4][5][6][7][8] Most of the time, this reversal of polarity [2a] involves the oxidation of the indole nucleus [2b-j, 3] or the presence of strong electron-withdrawing groups. [2k-m] In this context, our group developed several methods [3,4] to generate electrophilic indoles to overturn the innate nucleophilicity of indoles, [1a, 5] including the C3-regioselective FeCl 3 -mediated hydroarylation of NÀAc indole 1 (Scheme 1) [3] which was inspired by preliminary findings from Nakatsuka and co-workers.…”

“…[2k-m] In this context, our group developed several methods [3,4] to generate electrophilic indoles to overturn the innate nucleophilicity of indoles, [1a, 5] including the C3-regioselective FeCl 3 -mediated hydroarylation of NÀAc indole 1 (Scheme 1) [3] which was inspired by preliminary findings from Nakatsuka and co-workers. [6] We have recently demonstrated that this reaction proceeds via a polyactivated intermediate, in which the acetyl is activated by FeCl 3 to favour the delocalization of the nitrogen lone pair into the carbonyl system, and in which the C2=C3 bond is activated by a proton to induce a Friedel-Crafts reaction with arene 2 (Scheme 1). [7] During the optimization process of the hydroarylation of NÀAc indoles, we screened several Lewis acids and FeCl 3 proved to be rather exclusive to promote the desired reaction.…”

ChemInform Abstract: FeCl3‐Mediated Friedel—Crafts Hydroarylation with Electrophilic N‐Acetyl Indoles for the Synthesis of Benzofuroindolines.

“…[12] Based on this finding, we explored the coupling between N-acetyl skatole 7 a and p-cresol 5 a. Disappointingly, the use of up to six equivalents of AlCl 3 did not lead to any of the desired product. Benzofuroindoline-containing natural products.…”