Showing papers on "Carroll rearrangement published in 1991"
227 citations
TL;DR: This is the first to show that meta-Claisen rearrangement occurs preferentially even when a free para position is available, and can be interpreted in terms of the small bond energy of the breaking apical carbon-iodine (III) bond.
Abstract: Reported for the first time are the generation of allenyliodinanes and their reductive iodonio-Claisen rearrangement Reaction of propargylsilanes, germanes, and stannanes with aryliodinanes in the presence of BF 3 -Et 2 O undergoes a reductive iodonio-Claisen rearrangement under mild conditions, yielding o-propargyliodoarenes in good yields The reductive ortho propargylation probably involves the intermediate formation of allenyl(aryl) iodinanes, which undergo [3,3]-sigmatropic rearrangement The lack of crossover products argues for the intramolecularity of the rearrangement When both ortho positions of aryliodinanes are occupied with alkyl substituents, the reductive iodonio-Claisen rearrangement affords meta substitution products This is the first to show that meta-Claisen rearrangement occurs preferentially even when a free para position is available The reductive ortho propargylation of iodinanes takes place under much milder conditions than the Claisen rearrangement The lower activation energy associated with the iodonio-Claisen rearrangement of allenyl(aryl) iodinanes can be interpreted in terms of the small bond energy of the breaking apical carbon-iodine (III) bond
65 citations
TL;DR: In this paper, it was shown that the chiral auxiliary directed the approach of the crotyl fragment to the Si face of the (E )-N,O -ketene acetal.
38 citations
TL;DR: An advanced intermediate for the synthesis of the Laurencia oxonane natural product obtusenyne, namely the unsaturated nine-membered lactone 3, was efficiently prepared in seven steps from (E )-3-hexenoic acid as mentioned in this paper.
37 citations
26 citations
TL;DR: The orthoester Claisen rearrangement is used as a key reaction in the facile conversion of an acetaldehyde moiety stereospecifically into the (E)-4-methylhex-4-enoic acid side-chain of mycophenolic acid as discussed by the authors.
Abstract: The orthoester Claisen rearrangement is used as a key reaction in the facile conversion of an acetaldehyde moiety stereospecifically into the (E)-4-methylhex-4-enoic acid side-chain of mycophenolic acid.
20 citations
TL;DR: The Stereoselective Ciaisen rearrangement of a series of tertiary allylic sulphone esters is reported in this article, where the rearrangements are based on the Stereodelective Caisen decomposition.
Abstract: The Stereoselective Ciaisen rearrangement of a series of tertiary allylic sulphone esters is reported.
18 citations
01 Jan 1991
TL;DR: The most common use of the Beckmann reaction is in the rearrangement mode, and may be regarded as the nitrogen analog of the BaeyerVilliger reaction.
Abstract: The preeminence of the Beckmann reaction among oxidative synthetic transformations since its discovery1 over a century ago is borne witness by its frequent review.2–11 The reaction has found most widespread use in the rearrangement mode, and may be regarded as the nitrogen analog of the BaeyerVilliger reaction. Thus, nitrogen may be inserted into carbonyl carbon-α-carbon bonds of aldehydes and ketones via rearrangement of the derived oximes. The stereoselectivity of the rearrangement allows distinction to be made between the α- and α′-carbon atoms flanking a ketone group (Scheme 1).
16 citations
TL;DR: In this paper, the steroselective ester enolate (Carroll rearrangement of (E)-2-butenyl 2-methylacetoacetate, followed by ozonolysis and acetylation was completed by the synthesis of (+-)-4-epi-acetomycin.
16 citations
TL;DR: An ene-ester 5 prepared from L-malic acid was subjected to the ester-enolate Claisen rearrangement under Ireland's condition to give stereoselectively C16-C22 fragment 11 containing (E ) trisubstituted double bond as mentioned in this paper.
15 citations
TL;DR: The reaction of N-propadienylanilines with 3,5-dichloro-2,4,6-trimethylbenzonitrile oxide proceeds in a site-selective and regioselective fashion to give 5-substituted 4-methylene-4,5dihydroisoxazoles as mentioned in this paper.
Abstract: The reaction of N-propadienylanilines with 3,5-dichloro-2,4,6-trimethylbenzonitrile oxide proceeds in a site-selective and regioselective fashion to give 5-substituted 4-methylene-4,5-dihydroisoxazoles. The latter compounds (i) add a second molecule of nitrile oxide to afford 4,5′-spirobi-(4,5-dihydroisoxazoles) and (ii) isomerise to 4-(2-aminobenzyl)isoxazoles through a Claisen-type rearrangement.
TL;DR: In this article, the main product of the reaction of 7,11-epoxyisogermacrone 3 with BF 3 Et 2 O was found to be a new bicyclic carbon skeleton.
01 Jan 1991
TL;DR: The rearrangement of α-halo ketones under the influence of base was first described by Favorskii in 1892,1,2 and the general scope of the reaction and the mechanistic implications have been the subject of a number of reviews as mentioned in this paper.
Abstract: The rearrangement of α-halo ketones under the influence of base was first described by Favorskii in 1892,1,2 and the general scope of the reaction and the mechanistic implications have been the subject of a number of reviews.3–12 In its most generally useful form, α-halo ketones undergo skeletal rearrangement when treated with a nucleophilic base (hydroxide, alkoxide or amine) to produce salts, esters and amides respectively Scheme 1. With polyhalogenated ketones unsaturated acid derivatives are produced, as shown in Scheme 2.
TL;DR: In this article, a highly stereo and enantioselective approach to clerodin 1, an insect antifeedant, is described, where the key step involved the stereospecific formation of the C9-C11 bond, at an early stage of the synthesis, using a Claisen rearrangement.
TL;DR: In this paper, the thermal Claisen rearrangement of the Z-isomer (5-Z) of 3,5,6-trideoxy-1,2-O-isopropylidene-3-C-methyl-α-D-ribo-hept-5-eno-1-4-furanose with triethyl orthoacetate in the presence of propionic acid gave two rearrangements with a high level of diastereoselectivity (approximately 8.5 to 1).
TL;DR: In this article, the synthesis of primary and secondary allylic alcohols (differing in the degree of steric hindrance) and amide acetals (achiral and chiral) is reported.
Abstract: The synthesis of primary and secondary allylic alcohols (differing in the degree of steric hindrance) and of amide acetals (achiral and chiral) is reported. These compounds were used as substrates in the amide acetal Claisen rearrangement, and the effect of Lewis acids on the stereoselectivity of the reaction was studied. The rearrangement products have been applied to the synthesis of the mesembrane alkaloids (–)-mesembranone, rac-O-methyljoubertiamine and joubertiamine.
TL;DR: The molecular rearrangement of the ketones (1, (10, and (19) to phenanthrene derivative (3) and decalin derivative (11, and 12) is respectively described in this article.
TL;DR: In this paper, the chirality of an anhydro sugar was transferred to the newly formed asymmetric carbon atom in the Claisen rearrangement of the crotyl ether 14c.
TL;DR: In this article, a method was developed for effecting rearrangements of allylacetoacetates to γ,δ-unsaturated ketones (Carroll rearrangement) and allylaryl ethers to the corresponding allylphenols (Claisen rearranging) under conditions of adsorption on aluminum oxide and silica gel.
Abstract: A method has been developed for effecting rearrangements of allylacetoacetates to γ,δ-unsaturated ketones (Carroll rearrangement) and allylaryl ethers to the corresponding allylphenols (Claisen rearrangement) under conditions of adsorption on aluminum oxide and silica gel. The method provides a sharp reduction of the temperature of these reactions and improvement of their efficiency.
TL;DR: Using the LCAO MO method in the MNDO approximation, the authors compared the concerted [3, 3]-sigmatropic and stepwise mechanisms for the acid-catalyzed Claisen amino rearrangement.
Abstract: Using the LCAO MO method in the MNDO approximation, we have compared the concerted [3, 3]-sigmatropic and stepwise mechanisms for the acid-catalyzed Claisen amino rearrangement. The latter is preferred.
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.
Abstract: The Claisen sigmatropic rearrangement with glyco-organic substrates is greatly accelerated in water. Moreover, 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 paper, the authors investigated the application of the Claisen rearrangement of 5-allyloxyindole in the synthesis of polysubstituted indoles.
Abstract: In synthetic studies leading to the title compounds, application of the Claisen rearrangement of 5-allyloxyindole was investigated. Almost quantitative yields of Claisen rearrangement product were realized, and a strategy for oxidative cleavage of the allyl double bond to an indole-4-acetaldehyde derivative was developed. A new method for conversion of 2,3-dihydroindoles into indoles was utilized: air oxidation in a strongly basic environment. The Claisen rearrangement of allyloxyindoles is presented as a method having considerable potential utility in synthesis of a variety of polysubstituted indoles.
TL;DR: In this article, the interaction of 2-methylthiopentafluoropropene with allyl alcohol in the conditions of paper gives a mixture of the addition product (1) and the ester (2), formed as a result of [3, 3]-sigmatropic rearrangement of intermediate - the fluorocarbanion (A).
TL;DR: The acid halides of 1,2,4-oxadiazol-3-carbohydroxamic acids react with formaldehyde dimethylhydrazone to give the corresponding α-oximohydrazones, which with hydrochloric acid rearrange to yield the dimethyl hydrazone of 3-amino-4-formylfurazane as mentioned in this paper.
Abstract: The acid halides of 1,2,4-oxadiazol-3-carbohydroxamic acids react with formaldehyde dimethylhydrazone to give the corresponding α-oximohydrazones, which with hydrochloric acid rearrange to yield the dimethylhydrazone of 3-amino-4-formylfurazane. In the absence of an acid catalyst, the 5-trifluoromethyl derivative undergoes a rearrangement to give 1-dimethylamino-4-nitroso-3-trifluoroacetamidopyrazole.