Acid mediated coupling of aliphatic amines and nitrosoarenes to indoles

Abstract

Synthesis of indoles from the reaction of amines and nitrosoarenes.

Synthesis of Benzazepinoindole Derivatives via a One‐Pot Process of TiCl4‐Catalyzed Indole Alkylation/Pictet‐Spengler Cyclization

“…Under the optimized reaction conditions detailed in entry 4 of Table 2, the desirable products 4 b and 4 c were prepared in good yields of 48% and 54%, respectively. Similarly, halogen‐substituted aldehydes produced the corresponding products 4 d , [3a,6,7] 4 e , and 4 f in 54%, 48%, and 45% yields, respectively. Furthermore, the reaction of m ‐methoxybenzaldehyde gave rise to the expected product 4 g in 47% yield, while 4 h , [3a,6] 4 h’ were afforded in 23% and 20% yields from p ‐methoxybenzaldehyde and o ‐methoxybenzaldehyde due to low reactivity of the methoxy group.…”

“…13 C NMR (125 MHz, CDCl 3 ): δ 146. 5,139.3,138.5,137.8,135.6,134.8,129.8,129.0,128.5,127.8,127.3,123.7,123.5,121.8,119.5,118.3,110.8,110.7,62.3,28.9,6,7,7]azepino [3,4-b]indole (4 b). Compound 4 b was synthesized according to general procedure B using benzaldehyde (77.6 mg, 0.73 mmol) as an orange solid in 48% yield (36.6 mg, 0.12 mmol).…”

A Compilation of Synthetic Strategies to Access the Most Utilized Indoloquinoline Motifs

“…Jana group reported an acid-mediated annulation reaction of nitrosoarenes 16 and tetrahydroquinoline 17 and to synthesize indole derivatives 18 using 4-nitrobenzoic acid in toluene under refluxing conditions. [17] For the synthesis of indoloquinoline 1, nitrosoarenes reacted with tetrahydroquinoline to give the corresponding indole derivatives via CÀ C and CÀ N bond formation under metal-free conditions. Next, the indole substrates were treated with molecular iodine in the presence of cesium carbonate at room temperature to provide indoloquinoline products (Scheme 4).…”

Condensation-Based Methods for the C–H Bond Functionalization of Amines

“…Indole derivatives such as 175 and 176 can be prepared from secondary N-aryl amines and nitrosobenzenes, as described in a study by Jana and coworkers (Scheme 82). 139 The proposed reaction mechanism involves the formation of N-aryl-1aminoiminium ions 177 followed by redox-isomerization to 178 and subsequent formation of enamine 179. The latter then undergoes a [3,3]-sigmatropic rearrangement providing β-aryl imine 180.…”