Computational and Experimental Investigation of the Diels−Alder Cycloadditions of 4-Chloro-2(<i>H</i>)-pyran-2-one

Afarinkia, K.; Bearpark, Michael J.; Ndibwami, Alexis

doi:10.1021/jo0348827

Cited by 29 publications

(36 citation statements)

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“…It was shown by Afarinkia et al that 3-and 5-halo-2H-pyran-2-ones react with electron-rich, electron-deficient and also electron-neutral alkenes in a very regio-and stereoselective way, whereas 4-halo derivatives behave completely differently. [19] The 5-(4-methoxyphenyl)-substituted 2H-pyran-2-one (1e) proved to be the most reactive substrate in combination with alkyne 10, whereas the 5-acetyl-substituted analogues were found to be the least reactive. To our surprise, we found that a slight change in the structure of the alkyne appears to significantly alter the reactivity.…”

Section: Experimental Studymentioning

confidence: 99%

The Participation of 2H‐Pyran‐2‐ones in [4+2] Cycloadditions: An Experimental and Computational Study

et al. 2010

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Keywords: Cycloaddition / Density functional calculations / Donor-acceptor systems / Pyranones / Reaction mechanisms Experimental and computational DFT studies of the DielsAlder (DA) reaction mechanism for the series of 2H-pyran-2-ones 1 and non-symmetrically substituted alkynes 2, 10, and 11 were undertaken. Several 2H-pyran-2-ones 1 were treated with N,N-diethylpropynamine (2). The results point toward a polar and asynchronous two-step mechanism that is in line with the characteristics of a polar Diels-Alder (P-DA) reaction mechanism.[5] Unexpected formation of minor products 4a-d during the reaction of 1 with 2 can be rationalized by considering the easily passable torsion barrier around the newly formed C-C bond that enables two different cyclization modes. The charge transfer (CT) and global reactivity indices analyses demonstrated that in these reactions 2H-pyran-2-ones act as electrophiles and N,N-diethylpropyn-

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Section: Experimental Studymentioning

confidence: 99%

The Participation of 2H‐Pyran‐2‐ones in [4+2] Cycloadditions: An Experimental and Computational Study

et al. 2010

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“…There are a few reports in which the unstable bicyclic adduct has been isolated. [6][7][8] An electron donating group on the 2-pyrones ring favours the normal electron demand Diels-Alder reaction. The Diels-Alder reaction of 3- 30 hydroxy-2-pyrones is accelerated in the presence of a base due to the formation of better electron donating oxide anion.…”

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Unusual tandem sequence of oxa Diels–Alder reaction, retro Diels–Alder reaction, and oxa 6π-electrocyclic ring opening in the reaction of 6-amino-4-(4-methoxyphenyl)-2H-pyran-2-ones with benzaldehydes

Khatri

Samant

2015

RSC Adv.

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“…1, 2010 Besides this, the estimation of several chemical properties and reactivities indexes of dienes and dienophiles can be performed with good experimental agreement. [12][13][14][15] An evidence of the importance of this reaction to the development and application of some computational calculations is the large number of published papers involving considerations about the concerted and nonconcerted, synchronous and asynchronous mechanism nature of some Diels-Alder reactions. [15][16][17][18] Most of these studies attempt to explain some experimental results non-consistent with empirical rules or expected results concerning the selectivity.…”

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“…30 According to Alder's rule the major stereoisomer in Diels-Alder reactions is the one that is formed by maximum accumulation of double bonds in the transition state (through-space). [26][27][28][29][31][32][33][34] On the other hand, the endo product is usually less stable than exo.While the stereoelectronic interactions, involved in the transition state stability, are widely studied in the literature, 14,15,35 the same attention has not been dedicated to understand the stability of the products. One of the most used examples of the Diels-Alder reaction, which is listed in several Organic Chemistry textbooks, [36][37][38] is that between cyclopentadiene (1) and maleic anhydride which, at room temperature, gives only the endo adduct that is then converted at 200 o C to the thermodynamically more stable exo adduct through a retro Diels-Alder reaction.…”

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confidence: 99%

“…While the stereoelectronic interactions, involved in the transition state stability, are widely studied in the literature, 14,15,35 the same attention has not been dedicated to understand the stability of the products. One of the most used examples of the Diels-Alder reaction, which is listed in several Organic Chemistry textbooks, [36][37][38] is that between cyclopentadiene (1) and maleic anhydride which, at room temperature, gives only the endo adduct that is then converted at 200 o C to the thermodynamically more stable exo adduct through a retro Diels-Alder reaction.…”

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Revisiting the stability of endo/exo Diels-Alder adducts between cyclopentadiene and 1,4-benzoquinone

Tormena

Lacerda

Oliveira

2010

J. Braz. Chem. Soc.

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Neste trabalho é apresentada uma análise teórica detalhada da estabilidade relativa dos adutos endo/exo formados entre o ciclopentadieno (1) e a 1,4-benzoquinona (2). As coordenadas intrínsecas de reação (IRC) indicaram a presença de apenas um estado de transição para a reação, mostrando que se trata de um mecanismo concertado para ambos os adutos, endo 3 e exo 4. As energias dos adutos foram calculadas com um alto nível de teoria (CBS-Q) confirmando que o aduto endo é mais estável que o exo, o que está em desacordo com o que é observado para reações que usualmente seguem a regra de Alder. Uma análise estrutural eletrônica foi realizada através da metodologia NBO, a qual indicou que interações atrativas predominam sobre as interações estéricas repulsivas no aduto endo. Em resumo, para a reação de cicloadição estudada o aduto endo é o produto termodinâmico e cinético, o que pode ser confirmado também pelos dados experimentais mencionados neste trabalho.In this work it is presented a detailed theoretical analysis of the relative stability of endo/exo Diels-Alder adducts formed by the reaction between cyclopentadiene (1) and 1,4-benzoquinone (2). The intrinsic reaction coordinate (IRC) showed the existence of only one transition state for the reaction studied, for both endo 3 and exo 4 adducts. The energies of both adducts were obtained at high level of theory (CBS-Q) confirming that the endo adduct is more stable than exo, which is in the opposite way to the observed in reactions that usually follow Alder's rule. An electronic structure analysis was performed through NBO methodology, indicating that the attractive delocalization interaction predominates over the steric repulsive interaction in the endo adducts. In summary, for the studied cycloaddition reaction the endo adduct is the thermodynamic and kinetic product, which can be also confirmed by experimental data mentioned in this work.Keywords: Diels-Alder reaction, endo/exo stability, theoretical calculation, NBO analysis IntroductionThe Diels-Alder reaction is one of the most interesting and useful reactions found in organic chemistry in 20 th century. [1][2][3][4][5][6][7][8] This cycloaddition is widely used to construct, in a regio-and stereo-controlled way, a six-membered ring with up to four stereogenic centers. 1-8 Historically, in 1906 Albrecht 9 published the reaction between the cyclopentadiene (1) and 1,4-benzoquinone (2) as a 1:1 adduct. However, Albrecht's considerations about the structure of the obtained adduct were inconsistent. After several studies, in 1928 Otto Diels and Kurt Alder, 10 established a correct structure for the mono-and bis-adducts formed by the reaction between these compounds through a [4+2] cycloaddition, in opposition to the reactional course suggested by Albrecht: an 1,4-addition of cyclopentadiene (1) into 1,4-benzoquinone (2). Since then, the Diels-Alder reaction has appeared in more than 32,000 papers involving synthetic and theoretical approaches. 11In general, Diels-Alder reactions are excellent reactional models ...

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Computational and Experimental Investigation of the Diels−Alder Cycloadditions of 4-Chloro-2(H)-pyran-2-one

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Cited by 29 publications

References 29 publications

The Participation of 2H‐Pyran‐2‐ones in [4+2] Cycloadditions: An Experimental and Computational Study

The Participation of 2H‐Pyran‐2‐ones in [4+2] Cycloadditions: An Experimental and Computational Study

Unusual tandem sequence of oxa Diels–Alder reaction, retro Diels–Alder reaction, and oxa 6π-electrocyclic ring opening in the reaction of 6-amino-4-(4-methoxyphenyl)-2H-pyran-2-ones with benzaldehydes

Revisiting the stability of endo/exo Diels-Alder adducts between cyclopentadiene and 1,4-benzoquinone

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