Atom-Economic Synthesis of 4-Pyrones from Diynones and Water

Xü, Yanli; Teng, Qing‐Hu; Wei, Tong; Wang, Hengshan; Pan, Ying‐Ming; Ma, Xiangyi

doi:10.3390/molecules22010109

“…Then, the cyclization of diynone 20 was performed via acid-mediated reaction (with triflic acid) in the presence of water, as previously described. 37 The target 2-aryl-g-pyrone 2 was obtained with a good yield (52% in 7 steps) and was fully characterized by NMR, mass spectrometry and elemental analysis. Scheme 6.…”

Section: Methodsmentioning

confidence: 99%

“…Various synthetic routes affording to symmetrically or asymmetrically in 2,6 positions were already described in the literature according to classical methods such as: (i) the cyclocondensation of the dienol of 1,3,5-tricarbonyl compounds under mild acidic catalysis (i.e. Brønsted acids such as triflic acid or p-toluenesulfonic acid), 9,10 (ii) the cyclization of diynone, 11,12,13 or via an original pathway using an isoxazole intermediate. 14 Herein, we chose to implement the strategies involving either a diynone intermediate, as the most explored and documented pathway to form a g-pyrone ring, and the one involving an oxazole intermediate a priori faster and offering good yields.…”

Section: Synthesis Of 26-g-pyrone Analogue Of Cyclocurcuminmentioning

confidence: 99%

Synthesis and photoswitching properties of bioinspired dissymmetric gamma-pyrone, analogue of cyclocurcumin

Pecourneau¹,

Losantos²,

Monari

³

et al. 2021

Preprint

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Cyclocurcumin, a turmeric curcuminoid with potential therapeutic properties, is also a natural photoswitch that may undergo E/Z photoisomerization under UV light. In order to be further exploited in relevant biological applications, photoactivation under near infrared (NIR) irradiation is required. Such requirement can be met through opportune chemical modifications,and most notably by favoring two-photon absorption (TPA) probability. Herein, a general and efficient synthesis of a biomimetic 2,6-g-pyrone analogue of cyclocurcumin is described, motivated by the fact that molecular modeling previews an order of magnitude increase of the NIR TPA cross-section for the latter compared to the natural counterpart. Three retrosynthetic pathways have been identified (i) via an aryl-oxazole intermediate or via an aryl-diynone through (ii) a bottom-up or (iii) a top-down approach. While avoiding the passage through unstable synthons or low yield intermediate reactions, only the latest approach could conveniently afford the 2,6-g-pyrone analogue of cyclocurcumin, in ten steps and with an overall yield of 18%. The photophysical properties of our biomimetic analogue have also been characterized showing an improved photo-isomerization yield over the parent natural compound. The potentially improved non-linear optical properties, as well an enhanced stability, may be correlated to the enforcement of the planarity of the pyrone moiety leading to a quadrupolar D-p-A-p-D system.<br>

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“…Various synthetic routes affording to symmetrically or asymmetrically in 2,6 positions were already described in the literature according to classical methods such as: (i) the cyclocondensation of the dienol of 1,3,5-tricarbonyl compounds under mild acidic catalysis (i.e. Brønsted acids such as triflic acid or p-toluenesulfonic acid), 9,10 (ii) the cyclization of diynone, 11,12,13 or via an original pathway using an isoxazole intermediate. 14 .…”

Section: Synthesis Of 26-g-pyrone Analogue Of Cyclocurcuminmentioning

confidence: 99%

“…Then, the cyclization of diynone 20 was performed via acid-mediated reaction (with triflic acid) in the presence of water, as previously described. 37 The target 2-aryl-g-pyrone 2 was obtained with a good yield (52% in 7 steps) and was fully characterized by NMR, mass spectrometry and elemental analysis.…”

Section: Synthesis Of 26-g-pyrone Analogue Of Cyclocurcuminmentioning

confidence: 99%

Synthesis and Photoswitching Properties of Bioinspired Dissymmetric 2,6-Gamma-Pyrone, Analogue of Cyclocurcumin

Pecourneau¹,

Losantos²,

Monari³

et al. 2021

Preprint

View full text Add to dashboard Cite

Cyclocurcumin, a turmeric curcuminoid with potential therapeutic properties, is also a natural photoswitch that may undergo E/Z photoisomerization under UV light. In order to be further exploited in relevant biological applications, photoactivation under near infrared (NIR) irradiation is required. Such requirement can be met through opportune chemical modifications,and most notably by favoring two-photon absorption (TPA) probability. Herein, a general and efficient synthesis of a biomimetic 2,6-g-pyrone analogue of cyclocurcumin is described, motivated by the fact that molecular modeling previews an order of magnitude increase of the NIR TPA cross-section for the latter compared to the natural counterpart. Three retrosynthetic pathways have been identified (i) via an aryl-oxazole intermediate or via an aryl-diynone through (ii) a bottom-up or (iii) a top-down approach. While avoiding the passage through unstable synthons or low yield intermediate reactions, only the latest approach could conveniently afford the 2,6-g-pyrone analogue of cyclocurcumin, in ten steps and with an overall yield of 18%. The photophysical properties of our biomimetic analogue have also been characterized showing an improved photo-isomerization yield over the parent natural compound. The potentially improved non-linear optical properties, as well an enhanced stability, may be correlated to the enforcement of the planarity of the pyrone moiety leading to a quadrupolar D-p-A-p-D system.<br>

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“…8 However, one of the simplest and most atom-economical approaches involves the hydration/cyclization of diynones or the cyclization of acetylenic β-diketones. The first one has been developed by different authors toward the synthesis of 4pyrones using Brønsted acids, such as triflic 9 acid or ptoluenesulfonic acid, 10 as catalysts (Scheme 1, eq 2).…”

mentioning

confidence: 99%

Regiodivergent Hydration–Cyclization of Diynones under Gold Catalysis

Solas

¹

,

Muñoz

²

,

Suárez‐Pantiga

³

et al. 2020

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Skipped diynones, efficiently prepared from biomass -derived ethyl lactate, undergo a tandem hydra-tionoxacyclization reaction under gold(I)-catalysis. Reaction conditions have been developed for a switchable process that allows selective access to 4-pyrones or 3(2H)-furanones from the same starting diynones. Further application of this methodology in the total synthesis of polyporapyranone B was demonstrated.

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Atom-Economic Synthesis of 4-Pyrones from Diynones and Water

Abstract: Transition-metal-free synthesis of 4-pyrones via TfOH-promoted nucleophilic addition/cyclization of diynones and water has been developed. This transformation is simple, atom economical and environmentally benign, providing rapid and efficient access to substituted 4-pyrones.

Cited by 26 publications

References 89 publications

Synthesis and photoswitching properties of bioinspired dissymmetric gamma-pyrone, analogue of cyclocurcumin

Synthesis and photoswitching properties of bioinspired dissymmetric gamma-pyrone, analogue of cyclocurcumin

Synthesis and Photoswitching Properties of Bioinspired Dissymmetric 2,6-Gamma-Pyrone, Analogue of Cyclocurcumin

Regiodivergent Hydration–Cyclization of Diynones under Gold Catalysis

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