Preparation of indolylmethanes catalyzed by metal hydrogen sulfates

Abstract

Solid acids were developed and applied to the condensation reactions of indole with carbonyl compounds at ambient temperature. Tetra-(indolyl)methanes were obtained by the condensation reaction of indole with dialdehyde compounds.

<b>Application of Triton X-100 coated poly vinyl chloride as new solid phase for preconcentration of Fe³⁺, Cu²⁺ and Zn²⁺ ions and their flame atomic absorption spectrometric determinations</b>

“…Poly vinyl chloride high molecular weight was purchased from Fluka (Switzerland). The ligand was synthesized according to literature (Scheme 1) [23].…”

Silica-bonded S-sulfonic acid as a recyclable catalyst for chemoselective synthesis of 1,1-diacetates

“…In connection with our studies on the preparation and applications of solid acids in organic transformations [12][13][14][15][16], we were interested in finding a simple and efficient method for the synthesis of quinoxaline derivatives under mild conditions using silica bonded S-sulfonic acid (SBSSA) as a catalyst (Scheme 2). Scheme 2.…”

“…IR spectra were run on a Shimadzu Infra Red Spectroscopy FT-IR-8000. The 1 H and 13 C NMR was run on Bruker Avance (DRX 500 MHz and 400 MHz) instruments in CDCl 3 . Results are reported in ppm.…”

“…Despite the attractiveness of these reagents, to the best of our knowledge, there is no report on the application of these catalysts in quinoxaline synthesis. Following the line of our studies on the design and application of solid catalysts in chemical transformations [12][13][14][15][16], we wish to describe herein, the preparation of silica bonded S-sulfonic acid (SBSSA) as illustrated in Scheme 1, which was then used as catalyst for the synthesis of quinoxaline derivatives.…”

A green protocol for the synthesis of bis(indolyl)methanes catalyzed by succinic acid under microwave irradiation

“…Synthetically these compounds are obtained from the electrophilic substitution at 3-position of indoles with aldehydes and ketones. Over the past few years syntheses of this class of molecules under different conditions have been reported with promoters such as KHSO 4 -SiO 2, [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] NBS, 30 P 2 O 5 /SiO 2, 31 NanoSiO 2 -Ultrasonicirradiation, 32 [Bmim]Br/microwave, 33 Zeokarb-225, 34 [n-However, most of these reported methods deal with toxic materials and solvents, high cost, long reaction time and burdensome work up procedures. Keeping in view of the tremendous importance of bis(indolyl)methanes there emerge a consistent demand of developing reaction conditions possessing readily available nontoxic materials, shorter reaction time, and green solvents as environmentally benign substitutes in this area.…”