Expeditious, Mild and Solvent Free Synthesis of Bis(indolyl)methanes, Using a Mixture of Phosphorus Pentoxide in Methanesulphonic Acid

Abstract

Highly rapid and efficient synthesis of Bis(indolyl)methanes has been developed by using a mixture of phosphorus pentoxide in methanesulphonic acid (Eaton’s reagent) at ambient temperature under solvent free condition.

Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

“…The most common examples in literature for the reaction of the synthesis of BIMs under solvent-free conditions utilize either protic acids, such as camphorsulfonic acid (CSA) [44], diammonium hydrogen phosphate (DAHP) [45], Amberlyst 15 [46], P 2 O 5 /MeSO 3 H [47], p-sulfonic acid calix [4]arene [48], xanthan sulfuric acid (XSA) [49], H 5 PW 10 V 2 O 40 /pyridinosanta barbara amorphous-15 (SBA-15) [50], TiO 2 -SO 4 2− [51,52], humic acid [53] or Lewis acids, such as N-bromosuccinimide (NBS) [54], silica chloride [55], Ph 3 CCl [56], ZnO [57], La(NO 3 ) 3 •6H 2 O [58], V(HSO 4 ) 3 [59], Cu(ClO 4 ) 2 •6H 2 O [60], Fe/Al pillared clay [61], trimethylsilyl chloride (TMSCl) [62], BiCl 3 -loaded montmorillonite K10 [63][64][65][66][67], ZrO 2 -MgO [68] or CaO [69]. Silica gel is an intriguing solid support, since it is a low cost, commercially available and non-hazardous support, that can be employed in tandem with various traditional catalysts [70].…”

Eaton’s reagent catalysed alacritous synthesis of 3-benzazepinones

“…In the recent literature, Eaton's reagent emerged as one of the better reagent in organic synthesis for example in the synthesis of 3,4-dihydropyridin-2-(1H)-ones [17], quinolones [18], cardo poly[benzimidazoles] [19], 4-hydroxycoumarin [20], cyclopentanones [21], oxazole's [22], aryl mesylates [23], chromones and flavones [24], mono and bis-chalcones [25] and bis(indolyl)methanes [26]. It is also used as catalyst for Fisher-indole synthesis and Beckmann rearrangement process [19] (Figure 1).…”

A Green, Expeditious, One-Pot Synthesis of 3, 4-Dihydropyrimidin-2(1H)-ones Using a Mixture of Phosphorus Pentoxide-Methanesulfonic Acid at Ambient Temperature

“…In continuation of our efforts on developing environmentally benign, green methodologies for biologically active organic compounds [7–9], herein we report a rapid, ambient temperature, and solvent-free method for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones using Eaton's reagent. 3,4-dihydropyrimidin-2(1H)-ones, Biginelli compounds, have been synthesized by condensing aldehyde, ethylacetoacetate and urea or thiourea under acidic conditions [10].…”