The relation between the Claisen rearrangement of allyl ethers and their electronic structure

Marcinkiewicz, S.; Green, J.; Mamalis, P.

doi:10.1016/s0040-4020(01)92170-2

Cited by 53 publications

(13 citation statements)

References 30 publications

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“…[9] However,c ompared with the classic Cope rearrangement reaction, the aza-Copev ersion requires much harsherr eactionc onditions because more energy is essential to bring the nitrogen atom into the chair topology of the transition state. [10,11] Recent studies revealed that the quaternized "N" molecules could dramatically reduce the energy and enable the rearrangement to occur under milder conditions. [8,12] As an intriguing extension of these protocols, coupling of 3-substitutedindoles 1 with nucleophilic N,N-dimethylisobutenylamine and its analogues 2 would in situ produce essential quaternized Ni ntermediates, which could undergo as ubsequenta za-Coper earrangement.…”

Section: Resultsmentioning

confidence: 99%

“…Indeed, 1.5 hw as suitable for achieving am uch improved yield of 48 %. Accordingly,1 .5 hw as chosen for furthero ptimization.A mong different solvents ystems probed (Table 1, entries 8a nd [11][12][13][14], ac ombination of iPrOH/water (4:1) showed the best result with 51 %y ield Scheme2.Design of the N-alkylation-aza-Cope rearrangement-hydrolysis cascadep rocess for the synthesis of 2-reverse prenyl indoles.…”

Section: Exploration and Optimization Of The Proposed Tandem N-alkylamentioning

confidence: 99%

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Facile Installation of 2‐Reverse Prenyl Functionality into Indoles by a Tandem N‐Alkylation–Aza‐Cope Rearrangement Reaction and Its Application in Synthesis

Chen

Fan

Zhang

et al. 2015

Chemistry A European J

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An unprecedented tandem N-alkylation-ionic aza-Cope (or Claisen) rearrangement-hydrolysis reaction of readily available indolyl bromides with enamines is described. Due to the complicated nature of the two processes, an operationally simple N-alkylation and subsequent microwave-irradiated ionic aza-Cope rearrangement-hydrolysis process has been uncovered. The tandem reaction serves as a powerful approach to the preparation of synthetically and biologically important, but challenging, 2-reverse quaternary-centered prenylated indoles with high efficiency. Notably, unusual nonaromatic 3-methylene-2,3-dihydro-1H-indole architectures, instead of aromatic indoles, are produced. Furthermore, the aza-Cope rearrangement reaction proceeds highly regioselectively to give the quaternary-centered reverse prenyl functionality, which often produces a mixture of two regioisomers by reported methods. The synthetic value of the resulting nonaromatic 3-methylene-2,3-dihydro-1H-indole architectures has been demonstrated as versatile building blocks in the efficient synthesis of structurally diverse 2-reverse prenylated indoles, such as indolines, indole-fused sultams and lactams, and the natural product bruceolline D.

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Section: Resultsmentioning

confidence: 99%

Section: Exploration and Optimization Of The Proposed Tandem N-alkylamentioning

confidence: 99%

Facile Installation of 2‐Reverse Prenyl Functionality into Indoles by a Tandem N‐Alkylation–Aza‐Cope Rearrangement Reaction and Its Application in Synthesis

Chen

Fan

Zhang

et al. 2015

Chemistry A European J

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“…The thermal and acid catalysed rearrangement of p-substituted N-( l', 1 '-di-methylally1)anilines (p-substituent = H (5), CH, (6), iso-C,H, (7), C1 (S), OCH, (9), CN (lo)), of N-( l', l'-dimethylallyl)-2,6-dirnethylaniline (1 l), of o-substituted N- (1'-methylal1yl)anilines (o-substituent = H (12), CH3 (13), t-C4H9 (14)), of (E)and (Z)-N- (2'-butenyl)aniline ((E)and (2)- 16), of N-(3'-methyl-2'-butenyl)aniline (17) and of N-allyl- (1) and N-allyl-N-methylaniline (15) was investigated (cf: Scheme 3). The thermal transformations were normally conducted in 3-methyl-2-butanol (MBO), the acid catalysed rearrangements in 2~-0 , 1 N sulfuric acid.…”

Section: Discussionmentioning

confidence: 99%

“…C 82,70 H 10,41 N 6,890/0 Gef. C 82,62 H 10,71 N 7,anilin ( (47), 123 (loo), 108 (76), 69 (12). C12H17N0 (191,28) Ber.…”

Section: Schlussbemerkungmentioning

confidence: 99%

Untersuchungen über aromatische Amino‐Claisen‐Umlagerungen

Jolidon

Hansen

1977

Helvetica Chimica Acta

103

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Investigations on Aromatic Amino‐Claisen Rearrangements The thermal and acid catalysed rearrangement of p‐substituted N‐(1′,1′‐dimethylallyl)anilines (p‐substituent=H (5), CH3 (6), iso‐C3H7 (7), Cl (8), OCH3 (9), CN (10)), of N‐(1′,1′‐dimethylallyl)‐2,6‐dimethylaniline (11), of o‐substituted N‐(1′‐methylallyl)anilines (o‐substituent=H (12), CH3 (13), t‐C4H9 (14), of (E)‐ and (Z)‐N‐(2′‐butenyl)aniline ((E)‐ and (Z)‐16), of N‐(3′‐methyl‐2′‐butenylaniline (17) and of N‐allyl‐(1) and N‐allyl‐N‐methylaniline (15) was investigated (cf. Scheme 3). The thermal transformations were normally conducted in 3‐methyl‐2‐butanol (MBO), the acid catalysed rearrangements in 2N‐0,1N sulfuric acid. ‐ Thermal rearrangements. The N‐(1′,1′‐dimethylallyl)anilines rearrange in MBO at 200‐260° with the exception of the p‐cyano compound 10 in a clean reaction to give the corresponding 2‐(3′‐methyl‐2′‐butenyl)anilines 22–26 (Table 2 and 3). The amount of splitting into the anilines is <4% (10 gives ≃ 40% splitting). The secondary kinetic deuterium isotope effect (SKIDI) of the rearrangement of 5 and its 2′,3′,3′‐d3‐isomer 5 amounts to 0.89±0.09 at 260° (Table 4). This indicates that the partial formation of the new s̀‐bond C(2), C(3′) occurs already in the transition state, as is known from other established [3,3]‐sigmatropic rearrangements. The rearrangement of the N‐(1′‐methylallyl)anilines 12–14 in MBO takes place at 290–310° to give (E)/(Z)‐mixtures of the corresponding 2‐(2′‐Butenyl)anilines ((E)‐ and (Z)‐30,‐31, and ‐32) besides the parent anilines (5–23%). Since a dependence is observed between the (E)/(Z)‐ratio and the bulkiness of the o‐substituent (H: (E)‐30/(Z)‐30=4,9; t‐C4H9: (E)‐32/(Z)‐32=35.5; cf. Table 6), it can be concluded, that the thermal amino‐Claisen rearrangement occurs preferentially via a chair‐like transition state (Scheme 22). Methyl substitution at C(3′) in the allyl chain hinders the thermal amino‐Claisen‐rearrangement almost completely, since heating of (E)‐and (Z)‐16, in MBO at 335° leads to the formation of the expected 2‐(1′‐methyl‐allyl) aniline (33) to an extent of only 12 and 5%, respectively (Scheme 9). The main reaction (≃60%) represents the splitting into aniline. This is the only observable reaction in the case of 17. The inversion of the allyl chain in 16 ‐ (E)‐ and (Z)‐30 cannot be detected ‐ indicated that 33 is also formed in a [3, 3]‐sigmatropic process. This is also true for the thermal transformation of N‐allyl‐(1) and N‐allyl‐N‐methylaniline (15) into 2 and 34, respectively, since the thermal rearrangement of 2′, 3′, 3′‐d3‐1 yields 1′, 1′, 2′‐d3‐2 exclusively (Table 8). These reaction are accompanied to an appreciable extent by homolysis of the N, C (1′) bond: compound 1 yields up to 40% of aniline and 15 even 60% of N‐methylaniline ((Scheme 10 and 11). The activation parameters were determined for the thermal rearrangements of 1, 5, 12 and 15 in MBO (Table 22). All rearrangements show little solvent dependence (Table 5, 7 and 9). The observed ΔH≠ values are in the range of 34‐40 kcal/mol and ...

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“…However, such rearrangements usually take place with a significant rate enhancement when there is an additional alkyl group on the substrate (i.e., N-alkyl, N-allyl). Recently, Alajarín et al reported 2 the aromatic aza-Claisen rearrangement of N-allyl-1-naphthylamines under thermal conditions by utilization of the standard protocol of Marcinkiewicz et al 3 and Inada and Kurata 4 and the corresponding C-allyl product was eventually obtained in only 50% yield together with a considerable amount of starting material and cyclized product (Scheme 1). Therefore, it is evident that the aromatic aza-Claisen rearrangement remains largely unexplored under catalyzed conditions.…”

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confidence: 99%

Synthesis of Azepine- and Azocine-Annulated Heterocycles by Aromatic Aza-Claisen Rearrangement and Ring-Closing Metathesis

Majumdar¹,

Samanta²,

Chattopadhyay³

et al. 2009

Synthesis

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The relation between the Claisen rearrangement of allyl ethers and their electronic structure

Cited by 53 publications

References 30 publications

Facile Installation of 2‐Reverse Prenyl Functionality into Indoles by a Tandem N‐Alkylation–Aza‐Cope Rearrangement Reaction and Its Application in Synthesis

Facile Installation of 2‐Reverse Prenyl Functionality into Indoles by a Tandem N‐Alkylation–Aza‐Cope Rearrangement Reaction and Its Application in Synthesis

Untersuchungen über aromatische Amino‐Claisen‐Umlagerungen

Synthesis of Azepine- and Azocine-Annulated Heterocycles by Aromatic Aza-Claisen Rearrangement and Ring-Closing Metathesis

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