Phenylboronic Acid-Mediated Synthesis of 2H-Chromenes

Chauder, Brian A.; Lopes, Claudio C.; Lopes, Rosângela S. C.; Silva, Alcides J. M. da; Snieckus, Victor

doi:10.1055/s-1998-2042

Cited by 55 publications

(38 citation statements)

References 10 publications

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“…The bicyclic ring system of chromenes, like coumarin, has inspired a number of different synthetic approaches [5,6].…”

Section: Introductionmentioning

confidence: 99%

“…Other authors point out that when coumarin is treated with ethanolic sodium ethoxide at reflux, the lactone ring is opened (Scheme 3) to give 2-(ethylpropenoate)-phenoxide (5). Subsequent treatment of (5) with water and evaporation of the solvent brought about saponification of the ester and, with careful acidification, produces ocoumaric acid [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

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Process for the Obtention of Coumaric Acid from Coumarin: Analysis of the Reaction Conditions

López-Castillo¹,

Rojas-Rodríguez²,

Porta³

et al. 2013

ACES

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Coumaric acid can be obtained from basic hydrolysis of coumarin, through a reaction process consisting on opening the lactone ring and cis-trans isomerization. Parameters such as reaction time, temperature, NaOH concentration, solvent and reaction atmosphere, have been thoroughly studied and analyzed, in order to determine the appropriate conditions for the maximum conversion efficiency of coumarin into coumaric acid. Experimental results show that the best conditions are a 1 hour reaction time, at 160˚C, with a 20% sodium hydroxide aqueous solution, and in an inert reaction atmosphere.

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“…The bicyclic ring system of chromenes, like coumarin, has inspired a number of different synthetic approaches [5,6].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Process for the Obtention of Coumaric Acid from Coumarin: Analysis of the Reaction Conditions

López-Castillo¹,

Rojas-Rodríguez²,

Porta³

et al. 2013

ACES

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“…It has been reported that phenylboronic acid (PhB(OH) 2 ) is useful for benzopyran synthesis. 14,15) At first, we prepared precocene I and II by the reaction of methoxyphenols with 3-methyl-2-butenal using PhB(OH) 2 in acidic conditions. In addition, the dipyran analogues including natural products octandrenolone, clusiaphenone A, and relatives were prepared.…”

Section: Resultsmentioning

confidence: 99%

Effects of 2,2-dimethylchromenes against the feeding behavior of <i>Coptotermes formosanus</i> Shiraki

et al. 2013

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Precocene I and II are naturally occurring 2,2-dimethylchromenes that have a great influence on various insects. Using phenylboronic acid in acidic conditions, precocenes, natural products octandrenolone, clusiaphenone A, and relatives were prepared. In addition, the effects of synthetic chromene derivatives against Coptotermes formosanus Shiraki were evaluated in a no-choise test. The results demonstrate that they were able to induce antifeedant activities. It would seem that the precocene skeleton affects termites.

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“…Remarkably, this reaction also take place between phenols and , -unsaturated aldehydes under acid conditions. [27,28] Condensation between salicylaldehydes and unsaturated esters followed by a subsequent decarboxylation was also used [29][30][31] as well as oxidative cyclization of 2-allylphenols [32,33]. The present work illustrates the versatility of ytterbium triflate and its usefulness in improving the synthetic method mentioned above [3], which required the use of a pressure reactor and heating, into a room temperature experiment only requiring a stoppered glass tube.…”

mentioning

confidence: 88%

A simple two steps ytterbium triflate‐catalysed preparation of 2,2‐dimethyl‐2h‐chromenes from salicylaldehydes and 2‐methylpropene

Prado

Janin

Bost

2006

Journal of Heterocyclic Chem

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The preparation of various 2,2-dimethyl-2H-chromenes was achieved in two steps via an ytterbium triflate-catalysed reaction between salicylaldehydes, trimethylorthoformate and 2-methylpropene. From salicylaldehyde, two reaction products were characterised: 4-methoxy-2,2-dimethylchroman and 2-(1,3-dimethoxy-3-methylbutyl)phenol. The former compound probably results from a Lewis acid-catalysed [2+4] cycloaddition between the intermediate quinonemethide and 2-methylpropene whereas the latter may occur via a reaction related to a carbonyl-ene reaction between the quinonemethide and 2-methylpropene. Both compounds were subjected to a catalytic acidic treatment leading to 2,2-dimethyl-2H-chromene. Starting from various salicylaldehydes, the scope of this method was investigated.J. Heterocyclic Chem., 43, 1605Chem., 43, (2006.In the course of synthesis of biologically active chromene derivatives, [1] our attention was drawn [2] to a patent [3] reporting a simple preparation of 2,2-dimethyl-2H-chromene (2) using a reaction between salicylaldehyde (1) and 2-methylpropene catalysed by acidic silicaalumina catalysts at 150 °C or zinc chloride at 75°C. More recently [4], the preparation of furo[2,3-b]benzopyran 5 was achieved in excellent yield using the ytterbium triflate-catalysed reaction between salicylaldehyde (1), trimethylorthoformate and dihydrofuran 4. As illustrated in Scheme 1, this reaction is an example [5][6][7][8][9][10][11] We wish to report here the synthesis of various 2,2-dimethylchromenes via an ytterbium triflate-catalysed reaction between salicylaldehydes, trimethylorthoformate and 2-methylpropene.From the overnight reaction between salicylaldehyde (1), trimethylorthoformate, 2-methylpropene and ytterbium triflate in a sealed flask at room temperature, we could isolate and characterise compounds 6 and 7 in 27 and 14% yield respectively. In a control experiment, compound 6 was subjected to the reaction conditions but no ring opening into 7 took place. Moreover, from salicylaldehyde (1), no reaction was seen if trimethylorthoformate was omitted. From the results of these negative control experiments, we suggest that compound 7 occurs via a reaction related to a carbonylene reaction between the o-quinonemethide intermediate 3 and 2-methylpropene followed by a methanol addition on the resulting double bond. Carbonyl-ene reactions catalysed by lanthanide triflate have been reported [13,14] and an example of a competition between this reaction and a Diels-Alder cycloaddition was also observed [13]. An excellent review describes all the reactions that can be catalysed by lanthanides triflates [15]. As related intramolecular cycloadditions have been reported previously [9], including an iodine-catalysed example [10], we also tried iodine on our substrates but without success. In order to obtain the corresponding chromene, compounds 6 and 7 were heated to reflux in toluene in the presence of a catalytic amount of p-toluenesulfonic acid (PTSA). It is noteworthy that allowing the resulting methanol to distil fr...

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Phenylboronic Acid-Mediated Synthesis of 2H-Chromenes

Abstract: Condensation of phenols with but-2-enal and 3-methylbut-2-enal in the presence of phenylboronic acid in acetic acid-toluene solution leads to substituted and condensed 2H-chromenes, constituting a mild and advantageous complement to classical routes for this class of heterocycles.

Cited by 55 publications

References 10 publications

Process for the Obtention of Coumaric Acid from Coumarin: Analysis of the Reaction Conditions

Process for the Obtention of Coumaric Acid from Coumarin: Analysis of the Reaction Conditions

Effects of 2,2-dimethylchromenes against the feeding behavior of <i>Coptotermes formosanus</i> Shiraki

A simple two steps ytterbium triflate‐catalysed preparation of 2,2‐dimethyl‐2h‐chromenes from salicylaldehydes and 2‐methylpropene

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