Regiodivergent Hydration–Cyclization of Diynones under Gold Catalysis

Solas, Marta; Muñoz, Miguel Ángel; Suárez‐Pantiga, Samuel; Sanz, Roberto

doi:10.1021/acs.orglett.0c02892

“…27,35 The ynone 19 could undergo the addition of 1-propynylmagnesium bromide (9) to give the expected aryl-hexa-1,4-diyn-3-ol 15 with a yield of 89%. 11 The last step before the cyclization in g-pyrone was the oxidation of 15 in corresponding ketone 20 using MnO2. 11,36 Thus, according to this synthetic way the g-pyrone's precursor 20 was obtained with an overall yield of 66%.…”

Section: Methodsmentioning

confidence: 99%

“…11 The last step before the cyclization in g-pyrone was the oxidation of 15 in corresponding ketone 20 using MnO2. 11,36 Thus, according to this synthetic way the g-pyrone's precursor 20 was obtained with an overall yield of 66%. Then, the cyclization of diynone 20 was performed via acid-mediated reaction (with triflic acid) in the presence of water, as previously described.…”

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%

See 1 more Smart Citation

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%

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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“…Recently, methods for the preparation of pyrones based on the cyclization of acetylenyl-1,3-diketones have been actively developed [ 29 , 30 , 31 , 32 , 33 ], which allows the switchable preparation of 4-pyrones or furanones. Similar approach is the use of dibromo derivatives, which can react as synthetic equivalents of acetylenyl-1,3-diketones and undergo dehydrobromination reactions under basic conditions [ 34 , 35 , 36 , 37 ].…”

Section: Introductionmentioning

confidence: 99%

2-Aryl-6-Polyfluoroalkyl-4-Pyrones as Promising RF-Building-Blocks: Synthesis and Application for Construction of Fluorinated Azaheterocycles

Usachev

¹

,

Nigamatova

²

,

Mysik

³

et al. 2021

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A convenient and general method for the direct synthesis of 2-aryl-6-(trifluoromethyl)-4-pyrones and 2-aryl-5-bromo-6-(trifluoromethyl)-4-pyrones has been developed on the basis of one-pot oxidative cyclization of (E)-6-aryl-1,1,1-trifluorohex-5-ene-2,4-diones via a bromination/dehydrobromination approach. This strategy was also applied for the preparation of 2-phenyl-6-polyfluoroalkyl-4-pyrones and their 5-bromo derivatives. Conditions of chemoselective enediones bromination were found and the key intermediates of the cyclization of bromo-derivatives to 4-pyrones were characterized. Synthetic application of the prepared 4-pyrones has been demonstrated for the construction of biologically important CF3-bearing azaheterocycles, such as pyrazoles, pyridones, and triazoles.

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Regiodivergent Hydration–Cyclization of Diynones under Gold Catalysis

Cited by 39 publications

References 62 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

2-Aryl-6-Polyfluoroalkyl-4-Pyrones as Promising RF-Building-Blocks: Synthesis and Application for Construction of Fluorinated Azaheterocycles

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