The 1,3-dibromo-5,5-dimethylhydantoin (DBH) was found to efficiently catalyze the one-pot synthesis of highly functionalized tetrasubstituted furan derivatives by the reaction of 1,4-diarylbut-2-ene-1,4-diones and acetoacetates in i-PrOH as the solvent at 80 -908 for 3 -7 h. The products were formed in high yields (82 -95%) under mild and neutral conditions.Introduction. -Substituted furan derivatives are important synthetic intermediates [1] and are found as structural units in many natural products such as in kallolides [2], cembrenolides [3], pheromones [4], and polyether antibiotics [5]. These heterocycles have found applications in many pharmaceuticals, fragrances, and dyes [6]. Furan subunits have also been used as building blocks for a large number of heterocyclic compounds and as synthons in natural-product synthesis [7]. As a consequence, the synthesis [8 -11] and the applications [12 -15] of furan derivatives still attract the attention of organic chemists. The most common strategy involved in the synthesis of furans is the cyclization [16] of 1,4-dicarbonyl compounds. Of the various other methods, syntheses involving transition-metal salts have recently been described for the preparation of substituted furan derivatives [17]. Oh and co-workers [18] have synthesized highly substituted furans via Pt-catalyzed hydroxy-or alkoxy-assisted cyclization of 2-(alk-1-yn-1-yl)alk-2-en-1-ones. More recently, Jaisankar and coworkers reported a novel method for the preparation of highly substituted furans by InCl 3 -catalyzed nucleophilic addition followed by a cyclization reaction, although it was limited to specific substrate classes [19].
A novel procedure for the synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes through one-pot condensation of naphthalen-2-ol with arenecarbaldehydes in the presence of N-bromosuccinimide (NBS) as catalyst under solvent-free conditions is described.
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