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Showing papers on "Claisen rearrangement published in 1977"




Patent
08 Feb 1977
TL;DR: In this article, a phenylacetic acid derivative of formula I is allylated in the presence of a base in a solvent, e.g. acetone, to give a compound of formula III, which is then subjected to the Claisen rearrangement under heating at 100W300°C.
Abstract: NEW MATERIAL:A phenylacetic acid derivative of formula I (R 1 and R 2 are H or lower alkyl; M is carboxyl, carbamoyl, hydroxyaminocarbonyl or lower alkoxycarbonyl; A and B are H, lower alkyl or aryl). EXAMPLE: 3-(Thiazol-2-yl)-2-hydroxyphenylacetic acid. USE: Useful as a medicine having analgesic, anti-inflammatory, antipyretic, antithrombotic and antiallergic action, etc. with high safety. PROCESS: A compound of formula II is allylated in the presence of a base in a solvent, e.g. acetone, to give a compound of formula III, which is then subjected to the Claisen rearrangement under heating at 100W300°C. The reaction product is then alkylated with an alkyl halide in the presence of a base to afford a compound of formula IV, which is then oxidized in a mixed solvent of water with acetic acid in the presence of an oxidizing agent to give the compound of formula I . COPYRIGHT: (C)1984,JPO&Japio

20 citations




Journal ArticleDOI
TL;DR: In this article, a thermal rearrangement of erythroid and threoid ortho-Dienones was performed using column chromatography on silica gel and its relative configuration at C(1) or C(6) was deduced from the chemical shifts in their 1H-NMR-spectra.
Abstract: On the Stereochemistry of the Aromatic Claisen Rearrangement. Thermal Rearrangement of erythroid and threoid ortho-Dienones. Erythro- and threo-1-methyl-1-(1′-methyl-2′-propynyl)-2-oxo-1,2-dihydronaph-thalene (erythro- and threo-6) as well as erythro- and threo-2,6-dimethyl-6-(1′-methyl-2′-propynyl)-cyclohexa-2,4-dien-1-one (erythro- and threo-8) were obtained together with the corresponding aromatic ethers 5 and 7 by alkylation of 1-methyl-2-naphthol and 2,6-dimethyl-phenol, respectively in alcoholic potassium hydroxide solution with 1-methyl-2-propynyl p-toluenesulfonate (Scheme 2). The diastereoisomeric dienones 6 and 8 were easily separated by column chromatography on silica gel and its relative configuration at C(1) or C(6) and C(1′) deduced from the chemical shifts in their 1H-NMR.-spectra (Table 1). Hydrogenation of 6 and 8 using Lindlar catalyst yielded the corresponding erythro- and threo-configurated (1′-methyl-2′-propenyl)-dienones 10 and 13, respectively (Scheme 3) the thermal rearrangement of which were studied. The following results were obtained: threo-10 rearranged in benzene at 85–105° preferentially via a chair-like (C) transition state to yield 99,5% (E)- and 0,5% (Z)-(2′-butenyl) 1-methyl-2-naphthyl ether ((E)- and (Z)-14; ΔΔG(C/B) = −4,0 kcal/mol). On the other hand, erythro-10 when heated at 105-125° in benzene gave 84,7% (E)- and 15,3% (Z)-14, i.e. in this case a boat-like (B) transition state is favoured (G(C/B) = + 1,3 kcal/mol) (Scheme 5 and Table 2). The thermal rearrangement of dienones 13 led to the corresponding ethers 12 as well as p-allyl-phenols 11. Thus, heating of threo-13 at 20–42° in cyclohexane resulted in the formation of 2,5% of ether 12, consisting of 98% of the (E)- and 2% of the (Z)-isomer, and 97,5% of (E)-11 which contained, at a maximum, 0,5% of the (Z)-isomer, (Scheme 6 and Table 3). This means that both rearrangements occurred with a strong preference of the C transition state (G (C/B, phenol) = −3,3 kcal/mol). On the contrary, erythro-13 when heated at 42–68° in cyclohexane yielded a 3:2 mixture of ether 12 and phenol 11(Scheme 6). The ethereal part consisted of 88,0% of the (E)- and 12,0% of the (Z)-isomer which again shows that the B geometry predominated in the erythro transition state leading to the ether (G (C/B)= + 1,3 kcal/mol). In the phenolic part 36–40% of the (E)-isomer and 64–60% of (Z)-isomer were found which means that in the para-Claisen rearrangement of erythro-13 the C arrangement is only slightly favoured (ΔΔG (C/B)= −0,36 kcal/mol).

8 citations


Journal ArticleDOI
TL;DR: The β-formylation of an α-hydroxyanthraquinone is shown to be possible by thermally induced rearrangement of the allyl ether, migration of the olefinic bond, and ozonolysis as mentioned in this paper.
Abstract: β-Formylation of an α-hydroxyanthraquinone is shown to be possible by way of thermally induced rearrangement of the allyl ether, migration of the olefinic bond, and ozonolysis.

7 citations



Journal ArticleDOI
TL;DR: In this paper, allylic 3-phenylthio-2-propen-1-yl ethers(3) underwent [2,3]-sigmatropic rearrangement by treatment of n-butyllithium in tetrahydrofuran (THF) at −40 ∼ −50°C to give the corresponding allylic alcohols.
Abstract: Allylic 3-phenylthio-2-propen-1-yl ethers(3) underwent [2,3]-sigmatropic (Wittig-type) rearrangement by treatment of n-butyllithium in tetrahydrofuran (THF) at −40 ∼ −50°C to give the corresponding allylic alcohols (7). On the other hand, the allylic ethers 3 were treated with potassium tert-but oxide in tert-butyl alcohol-N,N-dimethylformamide (DMF) at room temperature to give the corresponding allylic enol ethers (12), which isomerized to the corresponding aldehydes (13) on heating in xylene by the Claisen rearrangement.

5 citations


Journal ArticleDOI
TL;DR: In this article, the enolate Claisen rearrangement of the α-methoxyacetate of the allylic alcohol was used to obtain the β,γ-unsaturated ester.
Abstract: The ester enolate Claisen rearrangement of the α-methoxyacetate of the allylic alcohol (2) followed by oxidative decarboxylation of the dianion derived from the resulting α-methoxycarboxylate provides an efficient preparation of the β,γ-unsaturated ester (5), and hence leads to (6), the functionality of which is common to many mono- and sesqui-tetrpenes.

5 citations


Journal ArticleDOI
TL;DR: In this article, the synthesis of 1-hydroxy-3,6,7-trimethoxy-2,8-bis-(2-oxoethyl)xanthone, first obtained from ozonolysis of dimethylmangostin, is described.
Abstract: The synthesis of the dialdehyde 1-hydroxy-3,6,7-trimethoxy-2,8-bis-(2-oxoethyl)xanthone, first obtained from ozonolysis of dimethylmangostin, is described. Xanthone formation by cyclisation of a benzophenone intermediate is followed by selective demethylations, allylation, and Claisen rearrangement. Oxidative cleavage of the allyl side chains in 2,8-diallyl-1,3,6,7-tetramethoxyxanthone, followed by demethylation with boron trichloride, gave the required dialdehyde (5). Some 13C n.m.r. spectra of xanthones are discussed.


Journal ArticleDOI
TL;DR: The Amino-Claisen-Umlagerung der Allyl-aniline (I), (III), (VIII) and (IV) in siedendem Xylol ergibt die im Formelschema angegebenen Verbindungen as discussed by the authors.
Abstract: Die Amino-Claisen-Umlagerung der Allyl-aniline (I), (III), (VIII) und (IV) in siedendem Xylol ergibt die im Formelschema angegebenen Verbindungen.

Journal ArticleDOI
TL;DR: In this paper, folgende Synthese beschrieben: O- Allylierung von α-Hydroxy-anthrachinon with Allylbromid zu (I), Claisen-Umlagerung zum Hydroxychinon (II), das einmal zum Propenylderivat (III) umgelagert bzw. methyliert wird [78% Gesamtausbeute, bezogen auf (I)].
Abstract: Alternativ zur bekannten Darstellung der Verbindung (VI) wird folgende Synthese beschrieben : O- Allylierung von α-Hydroxy-anthrachinon mit Allylbromid zu (I), Claisen-Umlagerung zum Hydroxychinon (II), das einmal zum Propenylderivat (III) umgelagert bzw. mit Dimethylsulfat zum Methylather (IV) methyliert wird [78% Gesamtausbeute, bezogen auf (I)].

Journal ArticleDOI
TL;DR: The Amino-Claisen-Umlagerung der Allyl-aniline (I), (III), (VIII) and (IV) in siedendem Xylol ergibt die im Formelschema angegebenen Verbindungen as mentioned in this paper.
Abstract: Die Amino-Claisen-Umlagerung der Allyl-aniline (I), (III), (VIII) und (IV) in siedendem Xylol ergibt die im Formelschema angegebenen Verbindungen.

Dissertation
01 Jan 1977
TL;DR: In this article, a 2-allyl-3, 5-cyclohexadienone produced by the Claisen rearrangement of a phenylallyl ether is described.
Abstract: This work is concerned with the involvement of the two possible intramolecular Diels-Alder adducts which can be formed from a 2-allyl-3, 5-cyclohexadienone produced by the Claisen rearrangement of a phenylallyl ether. One of these adducts has been invoked to account for the ortho-ortho ' transformation. Pentafluorophenyl allyl ether was chosen as the starting material, as it was envisaged that the fluorine atoms would a) block enolisation in the dienone intermediates; b) make the proposed Diels-Alder reaction more favourable by furnishing an electron def icient diene; and c) would help to stabilise small ring systems in the product. The thesis is divided into five parts. Chapter one reviews the literature and traces the mechanistic development of the Claisen re arrangement and the ortho-ortho' transformation. In Chapters two and three the isolation and characterisation of aromatic, bicyclic and tricyclic decomposition products, from the two possible intramolecular Diels-Alder adducts, are discussed. Chapters four and five describe the Claisen rearrangement in penta-fluorophenyl 2-methylprop-2-enyl and pentafluorophenyl 2-methylbut-3-en-2-yl ethers and suggest that the products formed can be accounted for by a mechanistic scheme which could be general.

Journal ArticleDOI
TL;DR: In this article, 1-Phenylthiovinyl-lithium adds to n-hexanal to give the allylic alcohol (II) that undergoes the Carroll and Claisen rearrangement with formation of the carbonyl compounds (IV) which can be converted into dihydrojasmone (VIa) and 2-n-pentylcyclopent-2-enone(VIb) by hydrolysis and cyclisation.
Abstract: 1-Phenylthiovinyl-lithium adds to n-hexanal to give the allylic alcohol (II) that undergoes the Carroll and Claisen rearrangement with formation of the carbonyl compounds (IV) which can be converted into dihydrojasmone (VIa) and 2-n-pentylcyclopent-2-enone (VIb) by hydrolysis and cyclisation.

Journal ArticleDOI
TL;DR: In this article, aus den Thiocarbonsaureamiden (I) mit (II) erhaltenen Sulfoniumbromide (III) ergeben bei der Behandlung mit 1,0-1,2 Molaquival.
Abstract: Die aus den Thiocarbonsaureamiden (I) mit (II) erhaltenen Sulfoniumbromide (III) ergeben bei der Behandlung mit 1,0-1,2 Molaquival.

Journal ArticleDOI
TL;DR: In this article, the Titelverbindungen (VIa bzw. (VIb) werden wie im Schema angegeben, ausgehend von den entsprechenden Thiolactamen (I) mit den Olefinen (II), synthetisiert.
Abstract: Die Titelverbindungen (VIa) bzw. (VIb) werden wie im Schema angegeben, ausgehend von den entsprechenden Thiolactamen (I) mit den Olefinen (II), synthetisiert.