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.
Second-Generation Process Research Towards Eletriptan: A Fischer Indole Approach
The development of a second-generation process for the synthesis of eletriptan via a Fischer indole cyclisation is described. The finalised process offers several potential advantages over the current route of manufacture including cost, throughput, and safety.
Heteropoly acids as useful recyclable heterogeneous catalysts for the facile and highly efficient aza-cope rearrangement of N-allylanilines
Abstract Heteropoly acid phosphomolybdic acid (H3Mo12O40P) has been found to be an excellent catalyst for aza-cope rearrangement of N-allylanilines. Various organic solvents and ionic liquids were tested as reaction media. Better results were obtained in ionic liquid reaction media in terms of reaction time and yield of the product. Catalyst could be efficiently recovered from the reaction and reused with negligible loss of catalyst activity even after two cycles. Short reaction time, ambient conditions, simple workup and high yield are some of the striking features of the present protocol.