Thermal Claisen rearrangement of aryl allenylmethyl ethers: synthesis of 2-(o-hydroxyaryl)buta-1,3-dienes and 4-methyl-2H-1-benzopyrans
01 Jan 1992-Journal of The Chemical Society, Chemical Communications (The Royal Society of Chemistry)-Iss: 24, pp 1760-1761
TL;DR: In this paper, aryl allenylmethyl ethers in diethylene glycol were rearranged to yield 2-(o-hydroxyaryl)buta-1,3-dienes and 4-methyl-2H-1-benzopyrans.
Abstract: Thermal Claisen rearrangement of aryl allenylmethyl ethers in diethylene glycol afforded 2-(o-hydroxyaryl)buta-1,3-dienes and 4-methyl-2H-1-benzopyrans in good yield.
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01 Jan 1996
45 citations
TL;DR: A new intramolecular para cycloaddition of arenes with allenes, yielding attractive rigid scaffolds bearing several reactive functionalities to build in further diversity, and was scaled up to multigram quantities without erosion of the typically high yields in photocycloadducts.
Abstract: In this work, we report on a new intramolecular para cycloaddition of arenes with allenes, yielding attractive rigid scaffolds bearing several reactive functionalities to build in further diversity. Bicyclo[2.2.2]octadiene-type products and benzoxepine acetals are formed in this reaction, in ratios and yields depending on the substitution pattern on the aromatic ring, the nature of the chromophore, and the tether. This unprecedented reaction has remarkable features that distinguish it from many other photochemical transformations: it is particularly robust with respect to substituents, it can be scaled up without a notable loss of efficiency, and it can lead to structures with a high degree of complexity in low to good yields. All photochemical precursors could be synthesized readily in three steps. We confirmed the compatibility of the nitrogen atom in the photocycloaddition step, which gives access to a bicyclo[2.2.2]octadiene scaffold with two points that allow further diversification. This reaction wa...
24 citations
TL;DR: An FeCl3-catalyzed allenic Claisen rearrangement/regio- and chemoselective aerobic dehydrogenative cyclization domino reaction is developed, providing a wide range of 2-aryl/alkyl, 3-(substituted-vinyl)naphtho[2,1- b]furans in high yields at 95-130 °C in an atom- and step-economic fashion.
16 citations
TL;DR: In this article, a review of reaction chemistry and new ring synthetic methods for pyranones is presented, which covers work published in the calendar year 2010 and includes new ring synthesis methods for trioxanes, tetraoxane, dioxanes, trithianes and oxathianes.
Abstract: The review covers work published in the calendar year 2010. Novel reaction chemistry and new ring synthetic methods for pyrans, [1]benzopyrans, dihydro[1]benzopyrans (chromenes, chromans), [2]benzopyrans, dihydro[2]benzopyrans (isochromenes, isochromans), pyranones, coumarins, chromones, xanthenes, xanthones, thiopyrans, dioxins. dioxanes, trioxanes, tetraoxanes, dithianes, trithianes, oxathianes are reviewed.
10 citations
TL;DR: Simple and mild methods for the synthesis of allenes, employing indium- and zinc-mediated dehalogenation reactions of vicinal dihalides in an aqueous solvent, are described.
Abstract: Simple and mild methods for the synthesis of allenes, employing indium- and zinc-mediated dehalogenation reactions of vicinal dihalides in an aqueous solvent, are described. By using these procedures, various allenylmethyl aryl ethers and monosubstituted allenes have been prepared in good to excellent yields.
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References
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448 citations
TL;DR: Le (bis-[(bromo-4 di-t-butyl-2,6)phenoxy methyl) aluminium peut etre utilise pour obtenir l'isomere (Z) alors que l'sisomeres (E) est produit avec le (bis-(diphenyl 2,6 phenoxy] methyl) aluminum as discussed by the authors.
Abstract: Le (bis-[(bromo-4 di-t-butyl-2,6)phenoxy methyl) aluminium peut etre utilise pour obtenir l'isomere (Z) alors que l'isomere (E) est produit avec le (bis-[diphenyl-2,6 phenoxy] methyl) aluminium
113 citations
TL;DR: The influence accelerante de l'eau comme solvant, sur la vitesse de la transposition de Claisen a ete demontree pour divers substrats as discussed by the authors.
Abstract: L'influence accelerante de l'eau comme solvant, sur la vitesse de la transposition de Claisen a ete demontree pour divers substrats
95 citations
TL;DR: The structures of new pyran derivatives obtained by the new ring-closure were confirmed by the melting point, infrared and ultraviolet spectra of the authentic samples which were synthesized by another routes.
Abstract: It has been reported that 2-naphthyl allylic ethers undergo the Claisen rearrangement to give naphthol derivatives. 2-naphthyl propargyl ether derivatives, _??_-O·CH2C≡C-R (R=H, CH3, Ph.), replacing the double bond of allylic ethers by a triple bond, do not undergo the Claisen rearrangement but a new ring-closure to give 3H-naphtho [2, 1-b] pyran derivatives. Moreover, 1-naphthyl derivatives, _??_O·CH2C≡C-Phalso undergo the same ring-closure to give 4-phenyl-2H-naphtho [1, 2-b] pyran. The structures of new pyran derivatives obtained by the new ring-closure were confirmed by the melting point, infrared and ultraviolet spectra of the authentic samples which were synthesized by another routes.
73 citations
TL;DR: This is the first to show that meta-Claisen rearrangement occurs preferentially even when a free para position is available, and can be interpreted in terms of the small bond energy of the breaking apical carbon-iodine (III) bond.
Abstract: Reported for the first time are the generation of allenyliodinanes and their reductive iodonio-Claisen rearrangement Reaction of propargylsilanes, germanes, and stannanes with aryliodinanes in the presence of BF 3 -Et 2 O undergoes a reductive iodonio-Claisen rearrangement under mild conditions, yielding o-propargyliodoarenes in good yields The reductive ortho propargylation probably involves the intermediate formation of allenyl(aryl) iodinanes, which undergo [3,3]-sigmatropic rearrangement The lack of crossover products argues for the intramolecularity of the rearrangement When both ortho positions of aryliodinanes are occupied with alkyl substituents, the reductive iodonio-Claisen rearrangement affords meta substitution products This is the first to show that meta-Claisen rearrangement occurs preferentially even when a free para position is available The reductive ortho propargylation of iodinanes takes place under much milder conditions than the Claisen rearrangement The lower activation energy associated with the iodonio-Claisen rearrangement of allenyl(aryl) iodinanes can be interpreted in terms of the small bond energy of the breaking apical carbon-iodine (III) bond
65 citations