Showing papers on "Claisen rearrangement published in 1986"
TL;DR: In this article, the removal of p-t-butyl groups from p-acetyl, p-carboxy-, and p-carbomethoxycalix [6] arenes and calix[8]arenes is described.
363 citations
TL;DR: In this paper, an approach to the total synthesis of the 14-membered macrolide antibiotic aglycon chlorothricolide is presented, which includes initial esterification across the C1 and C25 carbons followed by macrodilactonization across C17 and C14 carbons.
Abstract: An approach to the total synthesis of the 14-membered macrolide antibiotic aglycon chlorothricolide is presented. Key steps from the two halves to (±)-19,20-Dihydro-24-O methylchlorothricolide, methyl ester, ethyl carbonate include initial esterification across the C1 and C25 carbons followed by macrodilactonization across the C17 and C14 carbons. Ester enolate Claisen rearrangement and subsequent decarboxylation afforded the intact lactone. Functionalization of the top half is explored. The ester enolate Claisen rearrangement of propionate derivatives of resolved 1-(t-butyldimethylsilyl)-trans-2-butene-1-ol is reported. Subsequent protiodesilation of the reduced and protected Claisen products resulted in the formation of 2,3-dimethyl-4-pentenyl ethers. Thus, the secondary α-silyl alcohol has functioned as a chiral primary alcohol equivalent. The Claisen rearrangement of vinyl ethyl derivatives of 5-tert-butyl-1-(hydroxymethyl)-1-cyclohexene is reported. The standard allyl vinyl ether conditions as well as the triethyl orthoacetate and ester enolate variants of the Claisen rearrangement all resulted in the formation of cis(axial)-4-tert-butylcyclohexyl-substituted systems. Thus, in sterically unbiased cases, this [3.3] sigmatropic process results in the axial attachment of the side chain in a cyclohexyl system.
103 citations
TL;DR: Cephalotaxine (1) and its analogue (3) were stereoselectively synthesized from proline via the pyrrolobenzazepine (4) through Claisen rearrangement, cationic cyclization, and regio-and stereo-selective hydroxylation as mentioned in this paper.
61 citations
TL;DR: In this paper, the Claisen rearrangement of allyl vinyl ethers is catalyzed by PdCl2(CH3CN)2, provided that alkyl substituents protect the vinyl ether double bond from coordination by the metal catalyst.
52 citations
TL;DR: In this paper, a new method for the stereoselective synthesis of dihydropyrans of various substitution patterns is described, involving the Ireland ester enolate Claisen rearrangements of 6-alkenyl-1,4-dioxan-2-ones.
47 citations
TL;DR: In this paper, a new ring contraction process was proposed for macrocyclic ketene acetals, which is subject to high internal asymmetric induction (cf. lactones 7 → carbocycles 8) as well as relative asymmetric inductions in the rearrangements of keteneacetals derived from lactones 18, 23 and 27.
46 citations
45 citations
TL;DR: In this article, the transposition of glycolates d'alkyles is controle par un substituant chiral relie a l'hydroxyle du glycolate.
Abstract: Le cours stereochimique de la transposition Claisen de glycolates d'alkyles est controle par un substituant chiral relie a l'hydroxyle du glycolate
36 citations
32 citations
TL;DR: In this paper, a total synthesis of the mold metabolite ethisolide (1a) is described, wherein a glycolate ester enolate Claisen rearrangement and an acid-induced intramolecular bis-transesterification are key steps.
32 citations
TL;DR: The antifungal mold metabolites isoavenaciolide (1b) and avenaciolides (1c) have been synthesized in racemic form from a common precursor, α-methylene lactone 4, obtained via a glycolate ester enolate Claisen rearrangement.
TL;DR: In this paper, a substituant alkyle en position 2 d'un alcool allylique trans trisubstitue confere une diastereoselectivite importante importante sur la transposition Claisen d''un orthoester ou d´un acetal du systeme.
Abstract: Un substituant alkyle en position 2 d'un alcool allylique trans trisubstitue confere une diastereoselectivite importante sur la transposition Claisen d'un orthoester ou d'un acetal du systeme
TL;DR: Claisen rearrangement of the vinyl ketene acetals (7; a, R = CH2OSiPh2 But, or b, R= n-pentyl) which are generated in situ by syn-elimination of the corresponding selenoxides in refluxing xylene gave the eight-membered lactones (8a,b) as mentioned in this paper.
Abstract: Claisen rearrangement of the vinyl ketene acetals (7; a, R = CH2OSiPh2 But, or b, R = n-pentyl) which are generated in situ by syn-elimination of the corresponding selenoxides (6a,b) in refluxing xylene gave the eight-membered lactones (8a,b).
TL;DR: Synthese par reaction de (methoxy-4 trifluoro-1, 1, 1) pentene-3one-2 avec des derives du propene-2ol-1
Abstract: Synthese par reaction de (methoxy-4 trifluoro-1,1,1) pentene-3one-2 avec des derives du propene-2ol-1
TL;DR: In this paper, the total synthesis of deoxynivalenol is described, leading to the advanced intermediate, which includes a facile allyl alcohol epimerisation, a regioselective reductive deoxygenation, and a highly stereodelective Claisen allyl enol ether rearrangement.
TL;DR: In this article, a synthese de trimethyl-3,7,11 dodecanol-1 and du dimethyl- 3,7 pentadecanol-2 (pheromone de diprion pini) is applied.
Abstract: Application a la synthese de trimethyl-3,7,11 dodecanol-1 et du dimethyl-3,7 pentadecanol-2 (pheromone de diprion pini)
TL;DR: The optically active trans-octahydrodioxoinden-4-ylpropionic acid (6) was synthesized via the methylcyclopentanone (8) which was constructed through consecutive orthoester Claisen rearrangement of compounds derived from (R)-2,3-O-isopropylideneglyceraldehyde (1).
Abstract: The optically active trans-octahydrodioxoinden-4-ylpropionic acid (6) was synthesized via the methylcyclopentanone (8) which was constructed through consecutive orthoester Claisen rearrangement of compounds (9) and (12) derived from (R)-2,3-O-isopropylideneglyceraldehyde (1). Compounds (31) and (32), possessing trans-ring fusion, were prepared by Dieckmann condensation of the corresponding dimethyl esters (27) and (28) which were derived from the regio- and stereo-selective alkylation of the methylcyclopentanone (8), and then orthoester Claisen rearrangement of the allyl alcohol (26).
TL;DR: Synthese basee sur la transposition Claisen d'un cyclohexene carboxylate de cyclopentene-1yl methyle.
Abstract: Synthese basee sur la transposition Claisen d'un cyclohexene carboxylate de cyclopentene-1yl methyle
TL;DR: In this article, the 4-methoxybutadienylether of the allylic alcohol 13, which was made in 15 steps from D -glucose, afforded one major aldehyde 17 or 18 in good yield.
TL;DR: The allylic phosphate 4e has been shown to racemize 4-6% upon alkylation with the sodium lactone enolates of 1c and ent-1c in the presence of Pd(Ph3P)4.
TL;DR: The dextrorotatory antipode of the pheromone invictolide has been synthesized from R-3-methyl-γ-butyrolactone, which is employed as a stereochemical template for the addition of propionate units via a Claisen rearrangement and a palladium-catalyzed alkylation as mentioned in this paper.
TL;DR: An enantioselective route to the C(1)C(6) erythronolide unit 10 was described in this article, involving the dioxanone-to-dihydropyran enolate Claisen rearrangement (7 → 8 ), regio-and stereoselectively hydroboration to give 9a, and reductive fragmentation of the heterocyclic template (9c → 10 ).
TL;DR: In this paper, a right-wing equivalent 22 of the ionophore antibiotic indanomycin is described, wherein an unexpected retro hetero Diels-Alder/intramolecular Diels Alder pathway gives the desired product of the planned Claisen [3,3]-shift.
TL;DR: In this paper, a para-Claisen rearrangement and relactonisation of 4′-O-benzyl methyl coumarates was used to obtain linear prenylated umbelliferones.
Abstract: Heating 2′-O-prenylated derivatives of 4′-O-benzyl methyl coumarates (3) furnishes the corresponding linear prenylated umbelliferones (1) directly via sequential para-Claisen rearrangement and relactonisation.
TL;DR: In this article, the intramolecular cyclopentene annulation methodology was used to synthesize linear tricyclopentanoids of the hirsutane class or nonlinear members of the isocomene class.
Abstract: The intramolecular cyclopentene annulation methodology which combines the cyclopropanation of dienic diazoketones and the vinylcyclopropane rearrangement is utilized to synthesize linear tricyclopentanoids of the hirsutane class or nonlinear members of the isocomene class. The requisite diene precursors, endocyclic or exocyclic, respectively, are obtained from acylcyclopentenes via orthoester Claisen rearrangement of either allyl or propargyl alcohols. The scope and the generality of the method are indicated and experimental details are presented pertaining to the synthesis of precursory dienes for hirsutane and isocomene sesquiterpenes. Full details are disclosed concerning the total synthesis of epiisocomene and the synthesis of linearly fused precursors to coriolin sesquiterpenes.
TL;DR: Starting with 4-hydroxy-5-methyl coumarin, two compounds which were isolated from a Brachyclados species have been synthesized as discussed by the authors, and these compounds have been used to synthesize four different types of coumarins.