Synthesis and structure of 1-(2-bromophenyl)-2-chloro-3-(2-chloracetyl)-1H-indole

In the title indole derivative, C16H10BrCl2NO, the dihedral angle between the mean plane of the indole ring system and the mean plane of the disordered 2-bromophenyl ring is 77.6 (1)°. The non-H atoms of the chloracetyl group are essentially coplanar with the indole core. In the crystal, pairs of molecules are face-to-face embracedviatwo weak C—H...O hydrogen bonds, forming inversion dimers with an interplanar distance between two parallel indole planes of 3.360 (3) Å. These dimers are connected by head-to-head Cl...Cl intermolecular contacts to build a two-dimensional molecular sheet parallel to (101). Neighbouring molecular sheets are stacked together to construct the three-dimensional structure by further short Cl...Cl intermolecular contacts. The atoms of the bromophenyl group were refined as disordered over two sets of sites with refined occupancies of 0.61 (2) and 0.39 (2).

Regioselective synthesis of novel 2,3,4,4a-tetrahydro-1H-carbazoles and their cholinesterase inhibitory activities

The present study describes the regioselective synthesis of novel 2,3,4,4a-tetrahydro-1H-carbazoles (syn-2(a–q) and anti-3(a–b)) from l-menthone via Fischer indole synthesis.

Marine Sponge/H3PO4: As a Naturally Occurring Chiral Catalyst for Solvent-free Fischer-Indole Synthesis

Background

A new and efficient method have been developed for the synthesis of different indole derivatives from various ketones, having at least one hydrogen atom attached to each of their α-carbon atoms, and hydrazines in solvent-free conditions, using marine sponge/H₃PO₄ as a naturally occurring chiral catalyst.

Objectives

This study recommended the use of marine sponge/H₃PO₄ as a naturally occurring chiral catalyst for preparation of phenylhydrazones from ketones having one α-hydrogen and subsequent cyclisation of the products to indoles.

Materials and Methods

The reaction was carried out by mixing the phenylhydrazine, ketone, and marine sponge/H₃PO₄ powder in mortar and pestle; the mixture was ground at room temperature in an appropriate time until TLC show the completion of the reaction. The product extracted by CH₂Cl₂ and evaporation of solvent yields the products.

Results

In this research work, several indoles are synthesized using phenylhydrazine and aliphatic or aromatic ketone as starting materials, in the presence of marine sponge/H₃PO₄ powder as a natural catalyst under solvent-free condition.

Conclusions

We found marine sponge/H₃PO₄ to be an effective catalyst for indolisation of phenylhydrazones from ketones having α-hydrogens in solvent-free conditions.