Silica sulfuric acid mediated synthesis of naphtho[2,1‐b]furan derivatives and development of one‐pot multicomponent synthesis of substituted pyrazole derivatives

Abstract

Silica sulfuric acid (SSA) mediated synthesis of naphtho[2,1‐b]furan derivatives starting from β‐nitrostyrene derivatives and β‐naphthol derivatives under solvent‐free conditions have been developed. The scope of SSA as a heterogeneous catalyst is extended to one‐pot multicomponent reaction for the synthesis of functionalized pyrazole derivatives under solvent‐free conditions from readily available β‐nitrostyrene derivatives, acetyl acetone, and hydrazine hydrate. The synthetic methods have significant advantages such as solvent‐free conditions, simple operation, shorter reaction times, ease and clean isolation procedures, and very good yields of products.

A simple and efficient approach for the synthesis of functionalized naphtho[2,1-b]furan via an one-pot, three-component reaction between Meldrum's acid, arylglyoxals, and β-naphthol

“…The genotoxicity of (R7000) as well as that of other nitrofurans, is because of the presence of the nitro group, actively reduced in bacteria by endogenous nitroreductases, (R7000) is one of the strongest mutagens described for mammalians. 1 Since the naphthofuran scaffold displays several biological activities, the synthesis of this group of compounds has been realized via several routes, including various metal-catalyzed, [11][12][13] multicomponent methods, [14][15][16] carbon-oxygen bond formation reactions, 17 photochemical cyclizations, 18,19 Wittig reactions, 20 various catalysts, 21,22 cyclization reactions, 23,24 Diels-Alder cycloadditions, 25 and various other methods. [26][27][28][29][30] No doubt, all the existing methods are useful and effective, but have significant limitations such as, the use of an expensive catalyst, a special apparatus, low yields, difficult work-up, or a multistep synthetic sequence.…”

Polycyclic heteroaromatics via hydrazine-catalyzed ring-closing carbonyl–olefin metathesis

“…On the other hand, adduct 27 was generated only in low yield. Naphthofuran (28), which is known to have antitumor and oestrogenic properties, 21 was synthesized in good yield. Finally, pharmaceutically important structures such as benzocarbazole 22 29 and naphthoimidazole 23 30 could be accessed in moderate yields with increased catalyst loading.…”