Synthesis of 5-alkyl-3H-thiolen-2-ones and 5-alkyl-3H-furan-2-ones and condensation reactions at the heterocyclic methylene group

mentioning

confidence: 99%

“…12 Azomethine ylide was generated in situ from isatin and sarcosine by decarboxylation of the cyclic intermediate. 16 In this process, the formation of two dipoles 16,17 with differing ylide configurations A and B 2 is possible (Scheme 1).…”

mentioning

confidence: 99%

Reaction of arylmethylidene derivatives of 3H-furan-2-ones with azomethine ylide

Anis’kov

Kamneva

Zheleznova

et al. 2015

“…The arylmethylene-substituted 3H-furan-2-ones 1-4 and 5-R-3H-furan-2-ones 9 and 10 were obtained by the known method [4].…”

Section: Methodsmentioning

confidence: 99%

Synthesis of 6-amino-4-aryl- 2R-4H-furo[2,3-b]pyran-5-carbo- nitriles based on the condensation of 3-arylmethylene-3H-furan-2-ones with malononitrile

Anis’kova

Egorova

2009

The ability of 3-arylmethylene-3H-furan-2-ones to take part in Michael condensation as acceptors was used earlier in the reaction with cyclohexanone [1], acetylacetone [2], and acetoacetic ester [3].In a continuation of investigations into the reactivity of 3-arylmethylene-3H-furan-2-ones with methylene-active compounds their behavior in reaction with malononitrile was studied.The presence of the highly reactive methylene and cyano groups in malononitrile makes it possible to use this compound as a reagent for cyclizations leading to the formation of carbo-and heterocyclic compounds.The reaction of 5-aryl-3-arylmethylene-3H-furan-2-ones 1-4 with malononitrile was realized by heating the reagents in solution in DMSO in a molar ratio of 1:1 in the presence of catalytic amounts of triethylamine. 1-4 5-8Et 3 N 1, 5 R = C 5 H 11 ; 2, 6 R = Ph; 3, 7 R = p-Tol; 4, 8 R = 3-MeOC 6 H 4

“…The arylmethylene-substituted 3H-furan-2-ones 1a-c were obtained by the procedure in [4], and N-aryl-3H-pyrrolo-2-ones 2a,b by the procedure in [5]. .…”

Section: Methodsmentioning

confidence: 99%

Arylmethylene derivatives of 5-R-3H-furan-2-ones and N-aryl-5-R-3H-pyrrol-2-ones in reaction with acetylacetone

Egorova

Chadina

2007

Self Cite

The investigated compounds contain a conjugated oxoene fragment involving the exocyclic C=C bond and the double bond of the carbonyl group. Earlier [1] it was shown that the C=C and C=O bonds are fixed in the S-cis configuration, making it possible to use 3-arylmethylene-substituted furan-2-ones and pyrrol-2-ones in condensation reactions.The wide-ranging possibilities of using 3-arylmethylene-3H-furan-2-ones and N-aryl-3-arylmethylene-3H-pyrrol-2-ones in synthesis arise primarily from the presence of the two electrophilic centers. As a result of the delocalization of electron density in the C=C-C=O system these compounds behave as ambident electrophiles, and the addition of nucleophilic particles can take place in two directions, i.e., with attack at the carbon atom of the carbonyl group (1,2-addition) or at the β-carbon atom (1,4-addition).The relative reactivity of the 3-arylmethylene-3H-furan-2-ones and N-aryl-3-arylmethylene-3H-pyrrol-2-ones in 1,2-and 1,4-addition was examined by means of perturbation molecular orbital theory (PMO). According to this theory, if the electronic structure of the enone fragment is taken into account addition at the C=C group takes place under charge control while 1,4-addition (at the β-carbon atom) takes place under orbital control due to the maximum positive charge at the carbonyl carbon and maximum localization of the LUMO at the β-carbon atom.Orbital-controlled 1,4-addition is promoted by the increase in the degree of charge delocalization at the electrophilic center of the exocyclic C=C bond in the arylmethylene-substituted furanones, which is accompanied by a decrease in the LUMO energy level. For the initial arylmethylene-substituted 3H-furan-2-ones and N-aryl-3H-pyrrol-2-ones the electron densities of the LUMO at the exocyclic sp 2 -hybridized carbon atom were calculated by the LCAO-MO SCF method with PM3 parametrization in the MNDO approximation (Table 1). The results show that the electron density of the LUMO for the carbon atom of the exocyclic C=C bond is higher than that for the carbon atom of the carbonyl group, and on this basis it was concluded that 1,4-addition occurs in the case of the reaction with C-nucleophiles. __________________________________________________________________________________________