Ramkrishna Basak

Dry reaction of indoles with carbonyl compounds on montmorillonite K10 clay: a mild, expedient synthesis of diindolylalkanes and vibrindole A

Abstract Dry reaction of indoles 1a – c with aldehydes 2a – i , ketones 2j – o and an acetal 2p on M. K10 clay at room temperature furnished 3,3′-diindolylalkanes (DIAs: 3a – h , j – r ). The novel formation of tris(3-indolyl)methane 4 from 2i through tandem reactions and of the DIAs 6 and 8 from 1d through Plancher rearrangements were also observed.

Microwave-assisted Michael reactions of 3-(2′-nitrovinyl)indole with indoles on TLC-grade silica gel. A new, facile synthesis of 2,2-bis(3′-indolyl)nitroethanes

Abstract 3-(2′-Nitrovinyl)indole reacted with indole and 1- and 2-alkylindoles on TLC-grade silica gel under microwave irradiation to furnish in 7–10 min bis(indolyl)nitroethanes in high yields (70–86%). The same products were also obtained in 69–84% yields without microwave irradiation, but the reactions required 8–14 h for completion. Skatole was inert under both sets of conditions.

A sojourn in the synthesis and bioactivity of diindolylalkanes

The different synthetic routes to diindolylalkanes (DIAs), an important class of synthetic and natural products, their merits and demerits and the properties of the bioactive DIAs have been presented in this review which is the first of its kind in this field. The synthesis of the bioactive DIAs (3), streptindole (4), vibrindole A (6), 10 and 11 has also been included in this review.

A Facile and Efficient Synthesis of 2,2‐Bis(3′/2′‐indolyl)ethylamines and Three Bisindolic Natural Products

Abstract A simple and efficient synthesis of bis(indolyl)ethylamines and three bisindolic natural products, viz. hallucinogenic 6, genotoxic 7 and the alkanoic acid 8 has been developed by the reaction of indoles with appropriate carbonyl compounds on montmorillonite K10 clay.

Reaction of indole and alkylindoles with ceric ammonium nitrate on silica gel

Treatment of N-methylindole with CAN-on-SiO2 furnished 2,2-bis(N-methyl-3′-indolyl)-N-methylindoxyl, whereas that of skatole, N-methyl and N-ethyl skatoles produced the respective 2-nitroskatoles along with 6-nitroskatole and N-methyl-5-nitroskatole.