Brønsted acidic ionic liquid–catalyzed tandem trimerization of indoles: An efficient approach towards the synthesis of indole 3,3′‐trimers under solvent‐free conditions

Abstract

We have observed the role of 1-butane sulfonic acid-3-methylimidazolium tosylate, [BSMIM]OTs, as an organocatalyst for the tandem type trimerization of indoles to synthesize indole 3,3 0 -trimers under neat conditions. Using this developed protocol synthesis of indole trimers with various substituted indoles, which are biologically important, has been reported. From the control experiments and literature, a possible mechanism has been proposed via the generation of indolinium cation in the presence of the ionic liquid catalyst. The catalyst has been recycled for several times. The significant advantages of our methodology are clean reaction with very short time, no chromatography for purification, commercially available substrates, neat reaction conditions, and in the absence of metal. Using the protocol, the MDM2-p53 inhibitor has been synthesized in gram scale with high yield.

Iodine–TBHP mediated efficient synthesis of α-ketoamides from vinyl azides and amines under mild conditions

“…From the beginning of our research, we have given importance to the development of an environmentally benign and practical methodology. 33 Herein, considering the biological and synthetic importance of α-ketoamides, a simple and convenient approach has been developed for the direct synthesis of α-ketoamides based on the potential chemical reactivity of vinyl azides. To the best of our knowledge, the active site of aryl vinyl azides has not been explored to achieve ketoamide compounds.…”

Bis(trifluoroacetoxy)iodo benzene (PIFA)-promoted transamidation of carboxamides and carboxylic acids with amines

“…34 For the last five years, we have immensely engaged in the development of green and sustainable methodologies. [35][36][37][38][39][40][41] In this account, we have utilized the catalytic activity of PIFA 42 for the facile and collective transamidation of dimethylformamide, and formic acid.…”

Metal‐Free, PhI(OAc)2‐Promoted Oxidative C(sp2)−H Difunctionalization: Synthesis of Thioaminated Naphthoquinones

“…[39] For few years, our research group are engaged in developing several environmentally benign methodologies using the organocatalysts. [40][41][42][43] Presently, iodine(III) reagents including phenyliodonium(III) diacetate (PIDA) have been raised as an alternative to transition-metal catalysts. [44][45][46][47][48][49][50] Without any doubt, other than an oxidant this hypervalent iodine system has also shown catalytic property for carrying out many organic transformations.…”