40359-61-3Relevant academic research and scientific papers
Cascade Claisen and Meinwald Rearrangement for One-Pot Divergent Synthesis of Benzofurans and 2 H-Chromenes
Song, Liyan,Su, Qian,Lin, Xi,Du, Zhihui,Xu, Huiyou,Ouyang, Ming-An,Yao, Hongliang,Tong, Rongbiao
supporting information, p. 3004 - 3009 (2020/04/20)
A new cascade approach has been developed for the one-pot four-step divergent synthesis of polysubstituted benzofurans and 2H-chromenes, featuring a novel cascade aromatic Claisen rearrangement/Meinwald rearrangement/dehydrative or oxidative cyclization. This new method was demonstrated with 39 examples tolerating different substitutions at an epoxide, allylic ether, and aromatic ring, and we showcased its utility with the first total synthesis of natural product liparacid A in seven steps.
Gold-catalyzed rearrangement of allylic oxonium ylides: Efficient synthesis of highly functionalized dihydrofuran-3-ones
Fu, Junkai,Shang, Hai,Wang, Zhaofeng,Chang, Le,Shao, Wenbing,Yang, Zhen,Tang, Yefeng
supporting information, p. 4198 - 4202 (2013/05/08)
"Diazo" not needed: The title reaction results in the rearrangement of oxonium ylides, which were prepared from readily available homopropargylic allylic ethers instead of diazo compounds, through two different mechanisms: a concerted 2,3-sigmatropic rearrangement, or a stepwise 1,4-allyl migration followed by a Claisen rearrangement (see scheme). Copyright
Green synthesis of benzopyran-annulated thiopyrano[2,3-b ]thiochromen-5(4 H)-ones by domino Knoevenagel-hetero-Diels-Alder reaction
Majumdar,Taher, Abu,Ponra, Sudipta
scheme or table, p. 4043 - 4050 (2011/02/22)
Benzopyran-annulated thiopyrano[2,3-b]thiochromen-5(4H)-ones have been synthesized by the domino Knoevenagel-hetero-Diels-Alder (DKHDA) reaction of 4-hydroxydithiocoumarin with O-allylated salicylaldehyde and O-propargylated salicylaldehyde in aqueous medium. The reaction requires only a single step operation and is highly regio- and stereoselective providing potentially bioactive polycyclic heterocycles in high yields. Georg Thieme Verlag Stuttgart - New York.
Dehydrative intramolecular nitrone cycloaddition in confined aqueous media: A green chemical route to cis-fused chromano[4,3-c]isoxazoles
Chatterjee, Amrita,Hota, Sandip K.,Banerjee, Mainak,Bhattacharya, Pranab K.
supporting information; experimental part, p. 6700 - 6703 (2011/02/23)
An efficient synthetic route to the formation of cis-fused chromano[4,3-c]isoxazoles via dehydrative intramolecular 1,3-dipolar nitrone cycloaddition in organized aqueous media in the presence of a surfactant (viz. CTAB) as catalyst was developed, which indeed appeared to be green and a more sustainable method than the existing methods with the additional advantage of easy isolation of products.
Domino-Knoevenagel-hetero-Diels-Alder reactions: an efficient one-step synthesis of indole-annulated thiopyranobenzopyran derivatives
Majumdar,Taher, Abu,Ray, Krishanu
scheme or table, p. 3889 - 3891 (2009/09/28)
Rapid one-step synthesis of hitherto unreported indole-annulated pentacyclic heterocycles containing oxygen, nitrogen, and sulfur has been described by domino-Knoevenagel-hetero-Diels-Alder reaction. The reaction sequence provides a route to the synthesis of a novel type of polyheterocycles in excellent yields with high stereoselectivity.
Photoinduced free radical chemistry of the acyl tellurides: Generation, inter- and intramolecular trapping, and ESR spectroscopic identification of acyl radicals
Crich, David,Chen, Chen,Hwang, Jae-Taeg,Yuan, Hongwei,Papadatos, Aristotle,Walter, Robert I.
, p. 8937 - 8951 (2007/10/02)
Acyl tellurides are prepared in good to excellent yield by the reaction of sodium aryl tellurides with acyl chlorides, or mixed anhydrides, and are found to be moderately air-stable substances. In contrast to previous literature reports, acyl tellurides of aryl and vinyl carboxylic acids are found to be excellent sources of acyl radicals on photolysis with a simple white light source. The acyl radicals so generated may be trapped intermolecularly by dichalcogenides, or by TEMPO in excellent yield. Trapping by N-tert-butyl-α-phenyl nitrone produces a stable nitroxide radical which has been characterized by ESR spectroscopy. The very efficient trapping of acyl radicals by acyl tellurides themselves is demonstrated by a crossover experiment. Acyl tellurides are shown to participate in very efficient radical cyclization reactions onto alkenes with the formation of five-, six-, and eight-membered rings. The immediate products of the cyclizations onto alkenes are α-[(aryltelluro)methyl] ketones and the chemistry of these relatively unstable species is briefly described. Treatment with hydrogen peroxide affords α-methylene ketones in high yield. When elimination of the aryl telluro group is not possible the α-[(aryltelluro)methyl] ketones are stable species that may subsequently be employed in further radical chain reactions, for example with tributyltin hydride and methyl acrylate. Cyclization onto alkynes yields α-[(aryltelluro)methylene] ketones which are stable species and which take part in substitution reactions with higher order cuprates or with diphenyl diselenide.
Intramolecular 1,3-Dipolar Cycloadditions and Intramolecular Ene Reactions of 2-(Alkenyloxy)benzaldehyde Arylhydrazones
Shimizu, Tomio,Hayashi, Yoshiyuki,Kitora, Yoshitaka,Teramura, Kazuhiro
, p. 2450 - 2455 (2007/10/02)
2-(3-Aryl-2-propenyloxy)benzaldehyde (or 1-naphthaldehyde) arylhydrazones undergo an intramolecular cycloaddition reaction via their 1,3-dipolar tautomers, azomethine imines, to the alkenyl group.Initial cycloadducts were converted to dehydrogenated compounds under the reaction conditions.On the other hand, introduction of cyano or ethoxycarbonyl groups instead of the aryl group into 3-position of the ortho propenyloxy group gave 3-cyanomethyl-4-chromanone arylhydrazones or the corresponding ethoxycarbonyl derivatives, respectively.The formation of these hydrazones was interpreted in terms of intramolecular ene reaction.The course of the reactions depends on the nature of the alkenyl substituents.
