Synthesis of 3-Alkoxyindoles via Palladium-Catalyzed Intramolecular Cyclization of N-Alkyl ortho-Siloxyallylanilines

Update 1 of: Synthesis and Functionalization of Indoles Through Palladium-Catalyzed Reactions

“…The reaction has rarely been applied to the preparation of indoles. One of the few examples was the preparation of 3-alkoxyindoles (Scheme ).…”

C−C, C−O, C−N Bond Formation on sp2 Carbon by Pd(II)-Catalyzed Reactions Involving Oxidant Agents

“…Removal of the protecting group followed by trapping of the hydroxyl anion with alkyl halides afforded 3-alkoxyindoles. 182 The same method was applied to the synthesis of 1Hpyrrolo[3,2-b]pyridines 168 starting from 2-(1-hydroxyallyl)-3-aminopyridines (Scheme 128). 183 Protection of the hydroxyl group with TBDMS group followed by treatment with Pd(II)/ BQ gave the final products.…”

Heumann Indole Flow Chemistry Process

“…Although longer reactions times were necessary, Heumann cyclization of acid 3f under the flow conditions gave 3-methoxyindole 4f in 66% yield (vs 26% in batch; Scheme ). 3-Alkoxyindoles have previously been pursued due to their wide range of biological activities; however, their synthesis has generally required multiple steps and expensive metal catalysis. − The ability to obtain 3-alkoxyindoles directly from the corresponding anthranilates enriches the utility of the flow Heumann chemistry.…”