“In water” synthesis of bis(indolyl)methanes: a review

Effective Synthesis and Biological Evaluation of Natural and Designed Bis(indolyl)methanes via Taurine-Catalyzed Green Approach

“…As a result of this surge, numerous methods have been devised for the production of naturally occurring BIMs and their functionalized analogues (see Scheme 1 ). 7 , 11 , 33 , 34 Interestingly, most methods utilize 3-indole aromatic alcohols to afford symmetrical and unsymmetrical 3,3′-BIMs using a condensation strategy with appropriate nucleophiles. 19 , 35 In addition, the most common reaction protocols used in the synthesis include expensive and excess amounts of catalysts such as Cu-catalysts, 36 TsOH, Ga(OTf) 3 , Zn(OTf) 2 , etc.…”

“…As a result of this surge, numerous methods have been devised for the production of naturally occurring BIMs and their functionalized analogues (see Scheme ). ,,, Interestingly, most methods utilize 3-indole aromatic alcohols to afford symmetrical and unsymmetrical 3,3′-BIMs using a condensation strategy with appropriate nucleophiles. , In addition, the most common reaction protocols used in the synthesis include expensive and excess amounts of catalysts such as Cu-catalysts, TsOH, Ga­(OTf) 3 , Zn­(OTf) 2 , etc. − Several catalytic pathways were also developed to afford BIMs, which includes Bronsted or Lewis acid, methanol, iodine, electrolysis methods, metal salts, visible light, and enzymes. − Moreover, solid acidic catalysts such as Amberlyst, montmorillonite clay K-10, TiO 2 , ZrOCl 2 /SiO 2 , HClO 4 –SiO 2 , and P 2 O 5 /SiO 2 have also been investigated so far. − Over the last decades, methods for fabricating symmetrical and unsymmetrical 2,3′- and 3,3′-BIMs have primarily focused on the indolylation of 3-indolylmethyl alcohol, sulfone, malononitrile, 2,4,6-trimethoxybenzene, etc. with indole derivatives. − Although the divulged methodologies are phenomenal, they have some downsides, such as the need for expensive and higher catalytic loading, harsh reaction conditions, time-consuming reaction procedures, use of hazardous organic solvents, inadequate yields, and a constrained substrate scope.…”

Recent Advances on Direct Functionalization of Indoles in Aqueous Media

“…[46] Therefore, the scientific community has been exploring the infinite space of their synthesis and striving to build a green, efficient and economical synthetic route. [47,48] Most advanced methods are electrophilic substitution reactions of indole with various aldehydes or ketones. However, there are still drawbacks, such as strong acids, toxic solvents, and low yields.…”

“…Some natural alkaloids also have these indole motifs [46] . Therefore, the scientific community has been exploring the infinite space of their synthesis and striving to build a green, efficient and economical synthetic route [47,48] . Most advanced methods are electrophilic substitution reactions of indole with various aldehydes or ketones.…”

Increased catalytic activity through ZnMo7O24/g-C3N4 heterostructured assemblies for greener indole condensation reaction at room temperature

“…The indole alkaloids 3,4 , from lysergic 5 acid to vincristine 6 are one of the largest classes of alkaloids 7 , and they possess extended biological activity and drug discovery 8 . Among various reactions of indole 9,10 , the condensation reactions of indole with electron-deficient carbonyl compounds for the preparation of bis (indolyl) methanes and trisindolines has attracted and continues to attract interest in recent years 11,12 . In this context, various articles have focused on the preparation of target compounds employing homo and heterogeneous catalysts such as acidic ionic liquid immobilized on silica 13 , LiClO 4 14 , silica sulfuric acid 15 , magnetic metal-organic framework 16 , graphene 17 , Protic solvents 18 and heteropoly acids 19 .…”