Indoles from 2‐Methylnitrobenzenes by Condensation with Formamide Acetals Followed by Reduction: 4‐Benzyloxyindole

Abstract

Indoles from 2‐Methylnitrobenzenes by Condensation with Formamide Acetals Followed by Reduction: 4‐Benzyloxyindole intermediate: 6‐benzyloxy‐2‐nitrotoluene intermediate: (E)‐6‐benzyloxy‐2‐nitro‐β‐pyrrolidinostyrene and (E)‐6‐benzyloxy‐β‐dimethylamino‐2‐nitrostyrene product: 4‐benzyloxyindole intermediate: pyrrolidine enamine, mp 108–110° (MeOH), and N,N‐dimethylenamine

Formal Synthesis of Hapalindole O and Synthetic Efforts towards Hapalindole K and Ambiguine A

“…3,4,5 The resulting ketone was successfully elaborated into TMS-enol ether 5 with LHMDS and TMSCl in quantitative yields. Treating a solution of TMS-enol ether 5 and indole 1 in CH 2 Cl 2 at −78 °C with a 1M tin(IV) chloride solution afforded the expected tricycle (similar to 3 in Scheme 1) and subsequently closed to the desired dehydrated tetracycle 6 with aqueous HCl in MeOH in 45% yield over two-steps (Scheme 2).…”

Total Synthesis of Hapalindoles J and U

“…7 Treatment of 5 with NaH and TBSCl furnished the N -TBS-protected indole 11 (Scheme 5). Subjecting 11 to lithium-halogen exchange conditions, followed by addition of acetone furnished 12 in 99% yield with trace amounts of 13 obtained.…”

Alternative Approach to Synthesis of 3-(4-chloro butyl)-1H-indole-5-carbonitrile: A Key Intermediate of Vilazodone Hydrochloride, an Antidepressant Drug

“…[1] The broad spectrum of application of the indole nucleus has attracted great attention from several researchers, which led to the invention of numerous methods for the preparation of substituted indoles. [2][3][4][5][6][7][8][9][10][11][12][13] The Fischer indole synthesis, which was first discovered in 1883, is still considered as the most popular and one of the most general and efficient approaches to indole ring construction. [14,15] The Fischer indole synthesis involves the reaction of phenylhydrazine with an enolizable ketone or aldehyde to form the phenylhydrazone, which isomerizes to respective enamine (or ene-hydrazine).…”