Synthesis 12-Aryl or 12-Alkyl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-one derivatives catalyzed by dodecatungstophosphoric acid

Abstract

Um protocolo eficiente para a síntese de derivados de 12-aril ou 12-alquil-8,9,10,12-tetrahidrobenzo[a]xanten-11-one foi desenvolvido via reação de três componentes de aldeído, 2-naftol e 1,3-ciclohexadiona ou 5,5-dimetil-1,3-ciclohexadiona na presença de ácido 12-tungstofosfórico (H 3 PW 12 O 40 ) sem o uso de solvente. A presente metodologia oferece muitas vantagens como altos rendimentos, procedimento simples, baixo custo, curto tempo de reação e condições brandas.An efficient protocol for the synthesis of 12-aryl or 12-alkyl-8,9,10,12-tetrahydro-benzo [a] xanthen-11-one derivatives has been developed via three-component reaction of aldehyde, 2-naphthol and 1,3-cyclohexadione or 5,5-dimethyl-1,3-cyclohexadione in the presence of 12-tungstophosphoric acid (H 3 PW 12 O 40 ) under solvent-free conditions. The present methodology offers several advantages such as high yields, simple procedure, low cost, short reaction times, and mild conditions. Keywords: xanthene, multi-component reaction, 2-naphthol, aldehydes, 12-tungstophosphoric acid, heteropoly acid, solvent-free conditions IntroductionXanthenes and their derivatives have been received special attention due to their diverse array of biological activities such as anti-inflammatory, antibacterial and antiviral activities. [1][2][3] In addition to this, they can be employed as dyes, 4 intracellular pH indicators, 5 molecular probes in chemical biology, 6 and fluorescent materials for visualization of biomolecules. 7 In particular, the xanthone moiety is a core structure of a series of natural products with interesting biological and pharmacological activities. [8][9][10][11][12] Tetrahydroxanthenones are among the most important classes in the family of xanthones due to their distinctive structure and great potential for further transformations. 13,14 Consequently, the development of novel methods for the synthesis of these heterocyclic compounds has been received considerable interest in both organic and medicinal fields. [15][16][17][18] The three-component reaction of aryl aldehydes, 2-naphthol and cyclic 1,3-dicarbonyl compounds has appeared as a novel alternative method for preparation of tetrahydroxanthenones. 19 In this regard, NaHSO 4 • SiO 2 was utilized to catalyze this reaction to afford 12-aryl or 12-alkyl-8,9,10,12-tetrahydro-benzo[a]xanthen-11-one derivatives. However, this method needs to be further improved because some disadvantages such as relatively long reaction times and the use of harmful volatile organic solvent. Therefore, the development of efficient, mild and environmentally benign practical synthetic methods for accessing this type of heterocyclic compounds still remains a great need.In recent years, the application of solid acids in organic synthesis is becoming an area of growing interest. Heteropoly acids (HPAs) are strong solid acids, harmless to the environment and highly stable toward humidity and have flexibility in modifying the acid strength. 21 On the other hand, multi-component reactions (MCRs) offer significant advanta...

Efficient Synthesis of 12-Aryl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-one Derivatives Catalyzed byp-Dodecylbenzenesulfonic Acid in Aqueous Media Under Ultrasound Irradiation

“…From these results, we can deduce that the yields are in general similar or greater than those described in the literature. [8][9][10][11][12][13][14][15][16][17][18][19]22,23] For example, in the previous report, [22] the condensation of 4-chlorobenzaldehyde, 2-naphthol, and 5,5-dimethyl-1,3-cyclohexanedione catalyzed by TBAF at refluxing temperature in water for 3.5 h, the yield of 4 h was 92%, whereas present procedure needed only 100 min to give 4 h in 92% yield ( Table 2, entry h). In the reaction catalyzed by NaHSO 4 Á SiO 2 , [19] the condensation of benzaldehyde, 2-naphthol, and 5,5-dimethyl-1,3-cyclohexanedione was carried out with 87% yield under refluxing 1,2-dichloroethane for 4 h, whereas the present procedure offered the target product in 93% yield under ultrasound for 80 min ( Table 2, entry a).…”

“…[3] These compounds can be used as dyes, [4,5] as pH-sensitive fluorescent materials, [6] and in laser technology. [7] Synthesis of these compounds via three-component condensation of aldehyde, 2-naphthol, and cyclic 1,3-dicarbonyl compounds was carried out under different conditions, such as solvent-free reaction catalyzed by HBF 4 = SiO 2 , [8] I 2 , [9] para-toluenesulfonic acid (p-TSA), [10,11] InCl 3 , P 2 O 5 , [12] Zr(HSO 4 ) 4 , [13] H 3 PW 12 O 40 , [14] cyanuric chloride, [15] HClO 4 -SiO 2 , [16] ceric ammonium nitrate (CAN), [17] and refluxing in 1,2-dichloroethane catalyzed by Sr(OTf) 2 [18] or NaHSO 4 Á SiO 2 . [19] However, in spite of their potential utility, some of the reported methods suffer from some drawbacks, such as longer reaction time, expensive transition-metal catalyst, or organic solvent.…”

Facile synthesis of tetrahydrobenzoxanthenones via a one‐pot three‐component reaction using an eco‐friendly and magnetized biopolymer chitosan‐based heterogeneous nanocatalyst

“…Therefore, a few synthetic methods have been introduced for them . One of the best reported approaches for the preparation of tetrahydrobenzo[ a ]xanthene‐11‐ones is the one‐pot MCR of 2‐naphthol, aryl aldehydes and 5,5‐dimethyl‐1,3‐cyclohexanedione (dimedone) using various catalysts such as sulfamic acid, NaHSO 4 /ionic liquid ([bmim]BF 4 ), dodecatungstophosphoric acid, iodine, InCl 3 /P 2 O 5 and p ‐toluenesulfonic acid/ionic liquid ([bmim]BF 4 ) . Most of those methods suffer from some disadvantages such as harsh reaction conditions, tedious workup procedures, expensive or toxic chemicals, stoichiometric amounts of catalysts, long reaction times and low yields.…”

Application of silica-bonded imidazolium-sulfonic acid chloride (SBISAC) as a heterogeneous nanocatalyst for the domino condensation of arylaldehydes with 2-naphthol and dimedone

“…The one-pot multi-component condensation reaction between arylaldehydes, 2-naphthol, and dimedone (5,5-dimethylcyclohexane-1,3-dione) has been used as the best procedure for synthesis of 12-aryl-8,9,10,12-tetrahydrobenzo[a]-xanthen-11-one derivatives. Several catalysts have been used to promote this reaction, including ceric ammonium nitrate [11], proline triflate [12], NaHSO 4 ·SiO 2 [13], strontium triflate [14], Zr(HSO 4 ) 4 [15], dodecatungstophosphoric acid [16], iodine [17], InCl 3 /P 2 O 5 [18], p-toluenesulfonic acid/ionic liquid [19], RuCl 4 [20], Brønsted acidic ionic liquid [21], [Pyridine-SO 3 H]Cl [22], and tityl chloride [23]. Although several methods and catalysts for the preparation of 12-aryl-8,9,10,12-tetrahydrobenzo[a]-xanthen-11-ones are known, considering the different application of these compounds, search for finding efficient catalysts and methods for their synthesis is still of significance.…”