Showing papers on "Claisen rearrangement published in 1990"
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
70 citations
TL;DR: In this article, a new nouveau sulfinyl orthoacetate was used for conversion, dans un seul vase a reaction, de certains alcools allyliques en esters dienoates correspondants via des rearrangements de Claisen et β-elimination de sulfoxyde a 100 o C
Abstract: Utilisation d'un nouveau sulfinyl orthoacetate pour la conversion, dans un seul vase a reaction, de certains alcools allyliques en esters dienoates correspondants via des rearrangements de Claisen et β-elimination de sulfoxyde a 100 o C
70 citations
62 citations
TL;DR: A general synthetic strategy based upon thermally induced Claisen ring expansion as the pivotal step allows for rapid elaboration of the lauthisans in enantiomerically pure condition and proper absolute configuration as discussed by the authors.
42 citations
TL;DR: Le 18-hydroxy-17-methoxyyohimbane-16-carboxylate de methyle a ete prepare a partir de la pyridine as mentioned in this paper.
Abstract: Le 18-hydroxy-17-methoxyyohimbane-16-carboxylate de methyle a ete prepare a partir de la pyridine
40 citations
TL;DR: Aza-Claisen rearrangement of enolates of N-2-butenyl-N-butylpropanamides with high stereoselectivity (up to 995:05) was performed in this paper.
37 citations
TL;DR: The β-lactone (±)-ebelactone A has been prepared in 12 steps from diethylketone (9% overall yield) using a series of three boron enolate aldol reactions coupled with the Ireland ester enolate Claisen rearrangement.
36 citations
TL;DR: Synthese d'isocarbacycline a partir d'4-acetoxy cyclopent-«2»-enone and de 4-[t-butyldimethylsiloxy] non-«1]--enyl cuivre lithium.
Abstract: Synthese d'isocarbacycline a partir d'4-acetoxy cyclopent-«2»-enone et de 4-[t-butyldimethylsiloxy] non-«1»-enyl cuivre lithium
36 citations
TL;DR: A general synthetic strategy based upon thermally induced Claisen ring expansion as the pivotal step allows for rapid elaboration of the lauthisans in enantiomerically pure condition and proper absolute configuration.
Abstract: A general synthetic strategy based upon thermally induced Claisen ring expansion as the pivotal step allows for rapid elaboration of the lauthisans in enantiomerically pure condition and proper absolute configuration
35 citations
TL;DR: In this article, the Baeyer-Villiger oxidation was used to give after dehydration the corresponding vinylic-substituted lactones for precapnelladiene.
TL;DR: In this article, the synthesis of two synthetic intermediates from alkyl-3-hydroxy-2-methylene butanoate via transformations involving Claisen rearrangements is described.
TL;DR: In this paper, the authors used a tandem electrocyclic ring closure/Claisen rearrangement of the intermediate carbodiimide to give 1,9-diazaphenalene derivatives.
Abstract: Treatment of iminophosphrane 3, derived from ethyl α-azido-2-(allyloxy) cinnamate, with aromatic isocyanates in toluene at 150 o C leads to the corresponding isoquinoline derivatives 5 by a tandem electrocyclic ring closure/Claisen rearrangement of the intermediate carbodiimide. Fremy's salt promoted oxidation of compounds 5 yields the 5,8-isoquinolinequinone allides 6, which by heating undergo cyclization to 2H-pyrano [2,3-f] isoquinolines isocyanates to give the corresponding carbodiimides, which by thermal treatment at 150 o C undergo a consecutive electrocyclic ring closure/Claisen rearrangement/intramolecular amination process to give 1,9-diazaphenalene derivatives
Patent•
06 Feb 1990
TL;DR: In this paper, an electron-donative achromatic dye which develops color through reaction with a phenol hydroxyl group is allowed to coexist with a compound of 1-hydroxylphenylalkenylether which generates a 1,2-dihydroxyl aromatic body through Claisen rearrangement as expressed by a formula.
Abstract: PURPOSE:To obtain a heat-sensitive recording material which has a long shelf life and can be applied as a solution by allowing electron-donative achromatic dye which develops color through reaction with a phenol hydroxyl group to coexist with a compound of 1-hydroxyphenyalkenylether which generates a 1,2-dihydroxy aromatic body through certain Claisen rearrangement. CONSTITUTION:An electron-donative achromatic dye which develops color through reaction with a phenol hydroxyl group is allowed to coexist with a compound of 1-hydroxylphenylalkenylether which generates a 1,2-dihydroxyl aromatic body through Claisen rearrangement as expressed by a formula. The mixing ratio by weight of the electron-donative achromatic dye and the aromatic alkenylether compound is preferably between 1:50 and 1:1, especially between 1:10 and 2:3.
TL;DR: The Claisen rearrangement of allyl phenyl ethers with exceptionally bulky, oxygenophilic methylaluminum bis(4-bromo-2,6-di-tert-butylphenoxide) (reagent A) is found to exhibit an unusual behavior not observable in the ordinary thermal and Lewis acid-induced rearrangements as discussed by the authors.
TL;DR: In this article, the addition of allylic alcohols to aryl vinyl sulfoxides at room temperature gives 2-allyloxyethyl aryls, which, on heating, are converted into γ, δ-unsaturated aldehydes via allylic vinyl ethers.
TL;DR: In this article, the ability of glucose to function as a chiral auxiliary is illustrated in the preparation of 4-pentene-1,3-diol, obtained for the first time in pure enantiomeric form.
TL;DR: In this article, the authors compose du titre a partir d'isopropyl 3 methyl-1 methylene-2 cyclopentaneacetaldehyde via une transposition.
Abstract: Synthese du compose du titre a partir d'isopropyl 3 methyl-1 methylene-2 cyclopentaneacetaldehyde via une transposition Claisen d'isopropyl-7 hexahydro methyl-4a methylene-2 propenyl-7a cyclopenta [b] pyranne en isopropyl-1 dimethyl-3a,8 hexahydro cyclopentacyclooctenone-6
TL;DR: The E and Z isomers of (2R,4S,5R)-5-hydroxy-4-(3-hydrox-1-propenyl)-2-methyl-1,3-dioxane (3Z and 3E) were derived from 4,6-O-ethylidene-D-glucose (1), and their 5-Otert-butyldimethylsilyl derivatives (5Z and (5E) served as substrates for Claisen rearrangements with triethyl orthoacetate RE
Abstract: The E and Z isomers of (2R,4S,5R)-5-hydroxy-4-(3-hydroxy-1-propenyl)-2-methyl-1,3-dioxane (3Z and 3E), which were derived from 4,6-O-ethylidene-D-glucose (1), and their 5-O-tert-butyldimethylsilyl derivatives (5Z) and (5E) served as substrates for Claisen rearrangements with triethyl orthoacetate
TL;DR: In this article, the effect of solvent on the Claisen rearrangement of 4-propargyloxycoumarins has been examined, and the effect has been shown to be negligible.
TL;DR: Microwave-Induced Reactions of Organic Substrates in the Cage of Zeolites has been studied in this article, where the reaction rate of corresponding rearrangement, dehydrogenation and dehydration is dramatically enhanced as compared with reactions under thermal conditions.
Abstract: Microwave-Induced Reactions of Organic Substrates in the Cage of Zeolites
Microwave irradiation of compounds 1, 7, 15, 19, 23, and 24adsorbed on Y zeolites has been studied. The reaction rate of the corresponding rearrangement, dehydrogenation and dehydration is dramatically enhanced as compared with reactions under thermal conditions.
TL;DR: The known R lactone 4 has been transformed in 9 steps into optically pure 2, a molecule possessing the ring system characteristic of the crenulide diterpenes as mentioned in this paper.
TL;DR: The azanorbornenes (1) and (3) reacted with diphenylketene to give the 3-azabicyclo[4.3.0]-nonanones (7] and (5) respectively, while the spiro compound (9) afforded the cyclopentenol derivative (10) on reaction with the same ketene as mentioned in this paper.
Abstract: The azanorbornenes (1) and (3) reacted with diphenylketene to give the 3-azabicyclo[4.3.0]-nonanones (7) and (5) respectively, while the spiro compound (9) afforded the cyclopentenol derivative (10) on reaction with the same ketene.
TL;DR: A variety of γ-hydroxyvinylstannanes were subjected to the Eschenmoser Claisen rearrangement to produce allylstans including those bearing a silicon and tin on the same carbon as mentioned in this paper.
TL;DR: In this article, the precursors of the sesquiterpenes (α-cuparenone) and laurene (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12) were identified.
TL;DR: The Ireland and Eschenmoser variations of the Claisen rearrangement of various organotin compounds afforded tributylstannyl-substituted, γ, δ-unsaturated esters or amides in fair to good yields as discussed by the authors.
TL;DR: In this article, the methyl enol ether of 2-methylcyclohexanone reacts regiospecifically with the optically active forms of but-3-yn-2-ol and but-1,2-dienyl 2-enol.
Abstract: The methyl enol ether of 2-methylcyclohexanone reacts regiospecifically with the optically active forms of but-3-yn-2-ol and but-3-en-2-ol. (R)-But-3-yn-2-ol yields an approximately 4 : 1 mixture of (R)-2-methyl-2-(R-buta-1,2-dienyl)cyclohexanone and the corresponding SR compound. By contrast the but-3-en-2-ol reaction is ca. 96% enantioselective; (R)-but-3-en-2-ol gives (R)-2-(trans-but-2-enyl)-2-methylcyclohexanone and (S)-but-3-en-2-ol gives the corresponding (S)-cyclohexanone. These Claisen rearrangement products have been transformed into Robinson-type annulated ketones. Cleavage of some highly hindered esters has been carried out efficiently by sodium methylsulphinyl-methanide in dimethyl sulphoxide.
TL;DR: The Claisen rearrangement of the vinyl substituted ketene aminals as mentioned in this paper gave the homochiral unsaturated seven-membered lactams, which were generated in situ by selenoxide elimination of the aminal precursors.
Abstract: The Claisen rearrangement of the vinyl substituted ketene aminals 6 which were generated in situ by selenoxide elimination of the aminal precursors 5 in the presence of 1,8- diazabicyclo[5.4.0]undec-7-ene (DBU) gave the homochiral unsaturated seven-membered lactams 7 .
TL;DR: The introduction of an α-2]-propenyl substituent into a chiral 2-piperidineacetate has been effected both by enolate Claisen rearrangement of an allyl ester and by direct allylation of the intermediate lithium enolate [(7) → (8) + (9)] (Scheme 1).
Abstract: Introduction of an α-2-[propenyl] substituent into a chiral 2-piperidineacetate has been effected both by enolate Claisen rearrangement of an allyl ester and by direct allylation of the intermediate lithium enolate [(7) → (8) + (9)] (Scheme 1). These two approaches give largely the opposite stereochemistry at the newly created centre; subsequent hydroboration and cyclisation of ester (9) leads to (+)-lupinine (12).