Saccharin: an efficient organocatalyst for the one-pot synthesis of 4-amidocinnolines under metal and halogen-free conditions

Intramolecular redox cyclization reaction access to cinnolines from 2-nitrobenzyl alcohol and benzylamine via intermediate 2-nitrosobenzaldehyde

An efficient base-promoted synthesis of cinnolines from 2-nitrobenzyl alcohol and benzylamine via an intramolecular redox cyclization reaction. The formation of intermediate 2-nitrosobenzaldehyde plays an important role in this transformation.

Artificial sugar saccharin and its derivatives: role as a catalyst

The primary objective of this review was to demonstrate the significance of artificial sugar saccharin and its derivatives as catalysts for a wide variety of organic transformations. The application of saccharin and its derivatives represents a greener and superior catalytic approach for reactions. In particular, we were interested in bringing together the literature pertaining to these saccharin derivatives from a catalysis perspective. The present review reports synthesis of saccharin and its derivatives such as saccharin-N-sulfonic acid, sodium saccharin, N-halo saccharin, saccharin lithium-bromide, N-formyl saccharin, N-acyl saccharin, N-nitrosaccharin, N-SCF₃ saccharin, N-fluorosultam, N-phenylselenosaccharin, N-thiocyanatosaccharin palladium saccharin, DMAP-saccharin, and [Bmim]Sac. This catalytic application of saccharin and its derivatives includes reactions such as the Biginelli reaction, Paal-Knorr pyrrole synthesis, azo-coupling reaction, halogenations, domino Knoevenagel, Michael, deoximation reaction, catalytic condensation, functional group protection and oxidation etc. Also, these saccharin derivatives act as a source of CO, NH₂, SCN, SCF₃ and nitro groups. We reported all the available data on saccharin and its derivatives acting as a catalyst from 1957 to date.

A Green Alternative for Aryl Iodide Preparation from Aromatic Amines

BACKGROUND

In continuation of our previous work and the applications of saccharin, we encouraged to investigate the one-pot synthesis of the aryl iodides by the diazotization of the arene diazonium saccharin salts.

OBJECTIVE

Arene diazonium salts play an important role in organic synthesis as intermediate and a wide variety of aromatic compounds have been prepared using them. A serious drawback of arene diazonium salts is their instability in a dry state; therefore, they must be stored and handled carefully to avoid spontaneous explosion and other hazard events.

METHODS

The arene diazonium saccharin salts were prepared as active intermediates in situ through the reaction of various aryl amines with tert-butyl nitrite (TBN) in the presence of saccharin (Sac-H). Then, in situ obtained intermediates were used into the diazotization step without separation and purification in the current protocol.

RESULTS

A variety of aryl iodides were synthesized at a greener and low-cost method in the presence of TBN, Sac-H, glacial acetic acid, and TEAI.

CONCLUSION

In summary, a telescopic reaction is developed for the synthesis of aryl iodides. The current methodology is safe, cost-effective, broad substrate scope, and metal-free. All used reagents are commercially available and inert to moisture and air. Also, the saccharine and tetraethylammonium cation could be partially recovered from the reaction residue, which reduces waste generation, energy consumption, raw material, and waste disposal costs.

Catalytic Applications of Saccharin and its Derivatives in Organic Synthesis

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Saccharin (1,2-benzisothiazol-3(2H)-one-1,1-dioxide) is a very mild, cheap, commercially available, water soluble, environmentally benign and edible Brønsted acidic substance. Recently, with other utilities, saccharin and its derivatives were employed as catalysts for various organic transformations. In this review, catalytic applicability of saccharin and its derivatives under various reaction conditions is summarized.