Improved synthesis of 3‐aralkylidine‐5‐arylthiophen‐2‐(3<i>H</i>)ones

Miller, Gerald A.; Heindel, Ned D.; Minatelli, John A.

doi:10.1002/jhet.5570180638

Cited by 9 publications

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“…In the IR spectra of these compounds we observed three strong absorption bands in the region corresponding to carbonyl stretching vibrations, at 1731, 1709, and 1687 cm -1 . It was shown previously [15][16][17][18] that 5-arylfuran-2(3H)-ones readily react with carbonyl compounds to form condensation products at the α-methylene group. Taking into account the above stated, as well as the absence of sulfur in the product molecules (according to their elemental analyses), the products obtained from lactones Ia and Ib and thioacetamide were assigned the structure of 4-aryl-N-[1-(5-aryl-2-oxo-2,3-dihydrofuran-3-ylidene)ethyl]-4-oxobutanamides IXa and IXb, respectively (Scheme 2).…”

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Reaction of 5-arylfuran-2(3H)-ones with amines

et al. 2009

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5-(4-Chlorophenyl)-and 5-phenylfuran-2(3H)-ones reacted with guanidine carbonate at the methylene group in the unsaturated lactone molecule, leading to the formation of 4-(2-aryl-5-oxo-2,5-dihydrofuran-2-yl)-5-aryltetrahydrofuran-2-ones, while 5-(4-methylphenyl)furan-2(3H)-one under analogous conditions gave rise to N, N′-bis[4-(4-methylphenyl)-4-oxobutanoyl]guanidine. The reactions of 5-arylfuran-2(3H)-ones with thioacetamide afforded 4-aryl-N-{1-[5-aryl-2-oxo-2,3-dihydrofuran-3-ylidene]ethyl}-4-oxobutanamides. The corresponding N-(4-aryl-4-oxobutanoyl)thioureas were obtained by heating 5-arylfuran-2(3H)-ones with thiourea.Various nitrogen-containing heterocyclic systems are often synthesized following an approach based on the reaction of equimolar amounts of difunctional electrophiles with amines. 5-Arylfuran-2(3H)-ones I are synthetic equivalents of 1,4-bielectrophiles. Although studies on the properties of these compounds have been initiated long ago by Biedermann [1] and Fittig [2] in the end of the XIXth century, known reactions of 5-arylfuran-2(3H)-ones I with amines are strongly limited; examples of their reactions with hydrazine derivatives and primary and secondary alkyl-and arylamines have been reported; in some cases, these reactions led to the formation of pyrrole [3-5] and pyridazine derivatives [6]. We now report on the reactions of 5-arylfuran-2(3H)-ones Ia-Ic with 1,3-binucleophiles, namely guanidine, thiourea, and thioacetamide, which were expected to produce nitrogen-and sulfur-andnitrogen-containing heterocycles.It is known that heating of 5-arylfuran-2(3H)-ones I with amines results in opening of the lactone ring and formation of the corresponding 4-aryl-4-oxobutanoic acid amides [2,3,5]. 5-(4-Methylphenyl)furan-2(3H)-one (Ic) reacted with guanidine carbonate according to a similar scheme: fusion of a mixture of the reactants at 120-130°C gave a 4-(4-methylphenyl)-4-oxobutanamide derivative. The product structure followed from its 1 H NMR spectrum which contained signals from methylene protons as two triplets at δ 2.70 and 3.22 ppm ( 3 J = 6.5 Hz) and NH proton signal at δ 9.33 ppm, br.s. This pattern is typical of 4-aryl-4-oxobutanoic acid derivatives [7]. In the IR spectrum of the product we observed ν NH bands at 3350 and 3289 cm -1 . In keeping with the mass-spectral data, the product was diacyl-substituted guanidine (m/z 408 [M + 1] + ). The above spectral data are consistent with three isomeric structures:

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