Recent Contributions to Hetero Diels-Alder Reactions

Blond, Gaëlle; Gulea, Mihaela; Mamane, Victor

doi:10.2174/1385272820666160216000401

Cited by 69 publications

(32 citation statements)

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“…The first is a two‐step pathway, including the formation of zwitterionic intermediate I from the 1,4‐conjugated addition of 1b to 8a (path a) . The second one may occur through a concerted hetero‐Diels‐Alder cycloaddition (path b) …”

Section: Resultsmentioning

confidence: 99%

“…62,63 The second one may occur through a concerted hetero-Diels-Alder cycloaddition (path b). [64][65][66] Figure 2 depicts rotamers 1b-A and 1b-B of the chiral auxiliary 1b. The former corresponds to the conformation observed in the X-ray structure of 29b, in which the benzylic proton is quasi coplanar in relation to the plane of the heterocycle, leaving the methyl and phenyl groups at the beta and alpha positions, respectively.…”

Section: Reaction Mechanisms and Diastereoselectivity Of The Procesmentioning

confidence: 99%

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Enantiopure 4‐oxazolin‐2‐ones and 4‐methylene‐2‐oxazolidinones as chiral building blocks in a divergent asymmetric synthesis of heterocycles

et al. 2019

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Enantiopure 3‐((R)‐ and 3‐((S)‐1‐phenylethyl)‐4‐oxazoline‐2‐ones were evaluated as chiral building blocks for the divergent construction of heterocycles with stereogenic quaternary centers. The N‐(R)‐ or N‐(S)‐1‐phenylethyl group of these compounds proved to be an efficient chiral auxiliary for the asymmetric induction of the 4‐ and 5‐positions of the 4‐oxazolin‐2‐one ring through thermal and MW‐promoted nucleophilic conjugated addition to Michael acceptors and alkyl halides. The resulting adducts were transformed via a cascade process into fused six‐membered carbo‐ and heterocycles. The structure of the reaction products depended on the electrophiles and reaction conditions used. Alternative isomeric 4‐methylene‐2‐oxazolidinones served as chiral precursors for a versatile and divergent approach to highly substituted cyclic carbamates. DFT quantum calculations showed that the formation of bicyclic pyranyl compounds was generated by a diastereoselective concerted hetero‐Diels‐Alder cycloaddition.

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Section: Resultsmentioning

confidence: 99%

Section: Reaction Mechanisms and Diastereoselectivity Of The Procesmentioning

confidence: 99%

Enantiopure 4‐oxazolin‐2‐ones and 4‐methylene‐2‐oxazolidinones as chiral building blocks in a divergent asymmetric synthesis of heterocycles

et al. 2019

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“…The thia-Diels-Alder reactions constitute an important group of hetero-Diels-Alder reactions, and they can be used to synthesize six-membered sulfur-containing compounds. 1 They are of special interest for the preparation of 3,6-dihydro-2H-thiopyrans, which are known as relevant components of natural and biologically active products. 2 In general, thia-Diels-Alder reactions can be performed starting with thiabutadienes 3 or using thiadienophiles.…”

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confidence: 99%

“…1 H and 13 C NMR spectra were measured on a Bruker Avance III instrument (600 and 150 MHz, respectively) in CDCl 3 ; chemical shifts (δ) are given in ppm, coupling constants (J) in Hz. The multiplicity of the 13 C signals was deduced from DEPT supported by 1 H-13 C HMQC spectra 1. H NMR data are presented as follows: chemical shift, multiplicity (br = broad, s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet), coupling constant, integration.…”

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confidence: 99%

Thia-Diels–Alder reactions of hetaryl thioketones with nonactivated 1,3-dienes leading to 3,6-dihydro-2H-pyrans: evidence for a diradical mechanism

Mlostoń

Grzelak

Linden

et al. 2017

Chem Heterocycl Comp

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Dihetaryl thioketones possessing thiophen-2-yl and selenophen-2-yl rings react as "superdienophilic" reagents with nonactivated 1,3-dienes such as 2,3-dimethylbuta-1,3-diene, cyclopentadiene, and mixtures of isomeric hexa-2,4-dienes to produce the expected 2H-thiopyrans in moderate to excellent yields. In the latter case, the corresponding cis-2,2-dihetaryl-3,6-dimethyl-3,6-dihydro-2H-thiopyrans are formed as the sole products in a stereoconvergent thia-Diels-Alder reaction. A stepwise mechanism via delocalized diradical intermediates is postulated to rationalize the observed reaction course. Treatment of 4,5-dimethyl-2,2-di(thiophen-2-yl)-3,6-dihydro-2H-thiopyran with excess of m-CPBA at room temperature leads to the oxidation of the C=C bond and the sulfur atom in the six-membered ring.

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“…Hetero-Diels–Alder reactions are considered to be a powerful methodology widely explored for the synthesis of six-membered heterocycles [1–2] with numerous applications for the construction of complex molecules including naturally occurring products [3–4], drugs [5–6], agrochemicals [7], etc. In addition, asymmetric hetero-Diels–Alder reactions are of current interest [8–10].…”

Section: Introductionmentioning

confidence: 99%

First thia-Diels–Alder reactions of thiochalcones with 1,4-quinones

Mlostoń

Urbaniak

et al. 2018

Beilstein J. Org. Chem.

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Aryl and hetaryl thiochalcones react smoothly with 1,4-quinones in THF solution at 60 °C yielding the corresponding fused 4H-thiopyrans after spontaneous dehydrogenation of the initially formed [4 + 2] cycloadducts. In general, the yields of the isolated products were high. With 5-chloro-10-hydroxy-1,4-anthraquinone, the thia-Diels–Alder reaction occurred with complete regioselectivity. In the case of the reaction of vitamin K3 (menadione) with diphenylthiochalcone, the initial cycloadduct was isolated in 37% yield.

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Recent Contributions to Hetero Diels-Alder Reactions

Cited by 69 publications

References 0 publications

Enantiopure 4‐oxazolin‐2‐ones and 4‐methylene‐2‐oxazolidinones as chiral building blocks in a divergent asymmetric synthesis of heterocycles

Enantiopure 4‐oxazolin‐2‐ones and 4‐methylene‐2‐oxazolidinones as chiral building blocks in a divergent asymmetric synthesis of heterocycles

Thia-Diels–Alder reactions of hetaryl thioketones with nonactivated 1,3-dienes leading to 3,6-dihydro-2H-pyrans: evidence for a diradical mechanism

First thia-Diels–Alder reactions of thiochalcones with 1,4-quinones

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