Studies in claisen rearrangement : Novel thermal transformation of α-aryloxymethylacrylic acids and their derivatives
TL;DR: In this paper, the structure of α-Aryloxymethylacrylic acids and their derivatives has been revised on the basis of degradation studies, extensive spectral data and isolation of intermediates.
About: This article is published in Tetrahedron.The article was published on 1985-01-01. It has received 9 citations till now. The article focuses on the topics: Claisen rearrangement & Ene reaction.
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TL;DR: In this paper, the synthesis and Claisen rearrangement of methyl γ-aryloxycrotonates have been investigated and a number of them have been successfully rearranged to a mixture of Z and E 3-ethylidenebenzofuran-2(3H)ones in refluxing ethylene glycol.
15 citations
TL;DR: In this paper, a new high yielding route to substituted glutaric acid derivatives via an ester enolate Claisen rearrangement of allylic malonates is described.
12 citations
TL;DR: In this paper, the reaction of salicylaldehyde with propionic anhydride in the presence of anhydrous K2CO3 as catalyst afforded 3-methyl-2H-chromen-2-one (3-methylcoumarin) in good yields depending on the reaction conditions.
7 citations
Patent•
14 Mar 2014TL;DR: In this paper, various polymorphic forms and amorphous form of sodium 4-((3-(4-cyclohexylpiperazin-1-yl)-6-oxo-6H-anthra[1,9-cd]isoxazol-5-yl)amino)benzate, including the polymorphic form A, mixtures of the polymorphs, process for the preparation thereof and the use thereof in a pharmaceutical composition containing thereof.
Abstract: The invention relates to various polymorphic forms and amorphous form of sodium 4-((3-(4-cyclohexylpiperazin-1-yl)-6-oxo-6H-anthra[1,9-cd]isoxazol-5-yl)amino)benzate, including the polymorphic form A, mixtures of the polymorphs, process for the preparation thereof and the use thereof in a pharmaceutical composition containing thereof.
6 citations
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TL;DR: Salmiak as mentioned in this paper verwandelter Verbindungen in 0-Alkylderivaten and C-Derivate umzulagern, tritt diese Neigung bei den 0 A 11 y lderivaten i n stitrkstem Mn5e hervor.
Abstract: Bei Wiederauinahme meiner Arbeiten iiber die 0 A l k y l d e r i v a t e d e s A c e t e s s i g e s t e r s und verwandter Verbindungen hat sich ein bemerkenswerter Unterschied gezeigt, der zwischen den 0-Alkylderivaten mit den gewiihnlichen gesLt t ig ten A l k g l e n (Methyl, Athyl, Propyl usw.) einerseits und den %All yl'derivaten andererseits besteht. Wahrend die ersteren so gut wie gar keine Neigung zeigen, sich in die isomeren C-Derivate umzulagern, tritt diese Neigung bei den 0 A 11 y lderivaten i n stitrkstem Mn5e hervor. 0Al ly 1acetessigester wird beim Destillieren uber etwas Salmiak fast vollstiindig in 0Ally l ace t ess iges t e r verwandelt :
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TL;DR: In this article, a charge-induced [3s, 3s] sigmropic rearrangement of N-Allyl-2-methylaniline (12) forms on heating at 140° in xylene in the presence of zinc chloride 2.
Abstract: N-Allyl-2-methylaniline (12) forms on heating at 140° in xylene in the presence of zinc chloride 2-allyl-6-methylanline (19) as major compound and 4-allyl-2-methylaniline (20) as well as 2,7-dimethyl-indoline (21) as minor products. Compound 21 is also formed when 19 is heated in the presence of zinc chloride (scheme 2). That 19 arises from a charge-induced [3s, 3s] sigmatropic rearrangement of 12 – and 20 from two consecutive [3s, 3s]-sigmatropic transformations – follows from the reaction of N-crotyl-2-methylaniline (13) in the presence of zinc chloride at 140°. 2-(1′-Methylallyl)-6-methylaniline (22) and 4-crotyl-2-methylaniline (23) are formed exclusively. Small amounts of 2,3,7-trimethyl-indoline (24) and 2-(cis- and trans-1′-methyl-propenyl)-6-methylaniline (cis- and trans-25) are observed as by-products. Compound 24 arises from 22 in the presence of zinc chloride (scheme 3). Similar results are obtained when N-allyl and N-(2′-methylallyl)-N-methyl-aniline (14 and 15, respectively) are heated in the presence of zinc chloride. Whereas 14 gives nearly exclusively 2-allyl-N-methyl-aniline (28) and only small amounts of the corresponding 1, 2-dimethyl-indoline (29) and of 2-(cis- and trans-propenyl)-N-methyl-aniline (cis- and trans-27), 15 forms comparable amounts of 2-(2′-methylallyl)-N-methyl-aniline (30), 1,2,2-trimethyl-indoline (31), and 2-isobutenyl-N-methyl-aniline (32) (scheme 4). Compound 30, and also 32, are transformed into 31 on heating in the presence of zinc chloride.
Charge-induced aromatic amino-Claisen rearrangements are also observed when N-allylated anilinium tetraphenylborates are heated at 100–105° in hexamethyl phosphoric acid triamide. Thus, N-allyl- and N-crotyl-N, N-dimethyl-anilinium tetraphenylborate (16 and 17, respectively) yield 2-allyl- and 2-(1′-methylallyl)-N,N-dimethyl-aniline (33 and 34, respectively) besides small amounts of N, N-dimethyl-aniline. N-Cinnamyl-N, N-dimethyl-anilinium tetraphenylborate (18) gives, besides appreciable amounts of N,N-dimethyl-aniline, a mixture of 2-(1′-phenylallyl)-,2-cinnamyl-, and 4-cinnamyl-N, N-dimethyl-aniline (35, 36, and 37, respectively) in which the first two compounds predominate.
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42 citations