Intramolecular [3+4] allyl cation cycloaddition: Novel route to hydroazulenes

Giguere, R. J.; Duncan, Scott M.; Bean, Joseph M.; Purvis, Leslie

doi:10.1016/s0040-4039(00)82267-4

Cited by 43 publications

(14 citation statements)

References 30 publications

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“…These moieties act as C-1,3-dipole equivalent, because the allylsilane part is an allyl anion equivalent and the C¼O group of the acrylate or the OH-bearing C-atom of the allyl alcohol is a cationic center. By means of these structural features, various synthetic reactions have been developed [2], including the homo-Diels -Alder type [4 þ 3] cycloaddition developed by Hoffmann and coworkers [3] and Giguere and co-workers [4]. We have reported the syntheses of some five-membered ring compounds such as g-lactones [5], bicyclo [4.3.0]nonanes [6], and spiro [4.5]decanes [7], as well as cycloundecanes [8].…”

Section: Introduction -The 2-[(trimethylsilyl)methyl]acrylate (¼ 2-[mentioning

confidence: 99%

Correlation of Hydrolysis and Desilylation of 2‐[(Trimethylsilyl)methyl]acrylate Derivatives in Aqueous Alkali Solutions

Kuroda

Sunakawa

Muguruma

2008

Helvetica Chimica Acta

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Hydrolysis and desilylation reaction of 2-[(trimethylsilyl)methyl]acrylate (¼ 2-[(trimethylsilyl)methyl]prop-2-enoate) derivatives were studied to evaluate the effect of the presence/absence of a further conjugating substituent (Schemes 3 and 4 and Tables 1 and 2). The substrates having a nonconjugating substituent at the acrylate moiety were stable to dilute alkali conditions, and afforded simple hydrolysis products under concentrated alkali conditions. In contrast, both hydrolysis and desilylation occurred from the substrates bearing conjugated substituents at the acrylate skeleton. The difference in reactivity can be explained in terms of the stabilization of the intermediate anion. During the course of these projects, we previously obtained a-methylene-g-lactones via a cyclization of 2-[(trimethylsilyl)methyl]pentadienoate or the corresponding carboxylic acid [9]. Moreover, ethyl (2Z,4E)-4-methyl-2-[(trimethylsilyl)methyl]hexa-2,4-dienoate (1a) and ethyl (2Z,4E)-3-(cyclohex-1-en-1-yl)-2-[(trimethylsilyl)methyl]-hexa-2,4-dienoate (1b) were hydrolyzed to the corresponding acids 2a and 2b via a typical hydrolysis reaction, i.e., in the presence of aqueous KOH solution in MeOH (Scheme 1). However, the yields of the hydrolysis products 2a and 2b were low (26% for 2a and 31% for 2b). Although not mentioned in the report, the major products were the desilylated acids 3a and 3b. Since direct desilylation from an allylsilane moiety does not occur under such weak-base conditions [10], the desilylation reaction proceeded presumably via an intramolecular assistance of the ester group or its hydrolyzed carboxylate. Indeed, intramolecular attack of an electron-rich anion or related species at the Si-atom as a Lewis base [11] is considered to facilitate protodesilylation. The aim of the present study is to clarify the generality and the substituent effect of this

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Section: Introduction -The 2-[(trimethylsilyl)methyl]acrylate (¼ 2-[mentioning

confidence: 99%

Correlation of Hydrolysis and Desilylation of 2‐[(Trimethylsilyl)methyl]acrylate Derivatives in Aqueous Alkali Solutions

Kuroda

Sunakawa

Muguruma

2008

Helvetica Chimica Acta

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“…This result indicates an intimate involvement of the heterocyclicm oiety in the overall cycloaddition process. [16] Benzofuransa nd substituted furans also serve as viable reactionp artners in this Scheme (10,11), favoringt he trans-ring fusion. Dioxenes also performed well (12), in spite of the fact that these heterocycles are hydrolytically unstable in acidic medium, possibly explainingt he lower diastereoselectivity observed in this case.…”

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confidence: 99%

Stereoselective and Modular Assembly Method for Heterocycle‐Fused Daucane Sesquiterpenoids

Christiaens

Hullaert

Hecke

et al. 2018

Chemistry A European J

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A stereoselective synthetic method is reported for the molecular framework found in common daucane and isodaucane sesquiterpenoid natural products. The synthetic method constitutes a scalable, modular, and also asymmetric access to a complex natural product scaffold, wherein the substitution pattern and the stereochemistry can be adjusted simply by choosing different starting materials. The method allows the rapid introduction of diverse heterocyclic substructures such as (benzo)furans, (benzo)thiophenes, dithiins, thiazoles, and indoles, which actually also facilitate and direct the key intramolecular annulation step.

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“…[3,5] Alternative methods have involved the construction of the five-membered ring on the seven-membered ring and have employed metathesis, aldol condensation, ring expansion, or Nazarov cyclization. [7][8][9][10][11][12][13][14] [9] (Scheme 1, path b); [10] and Ahmar et al, [11a] Brummond et al [11b] and Mukai et al [11c] have reported various approaches employing allenic reactions of the Pauson-Khand type (Scheme 1, path c). [7][8][9][10][11][12][13][14] [9] (Scheme 1, path b); [10] and Ahmar et al, [11a] Brummond et al [11b] and Mukai et al [11c] have reported various approaches employing allenic reactions of the Pauson-Khand type (Scheme 1, path c).…”

mentioning

confidence: 99%

“…[3,6] Highly efficient approaches in which both rings are created in one pot have also been developed, most of them involve metal-catalyzed cycloaddition reactions (Scheme 1). [7][8][9][10][11][12][13][14] [9] (Scheme 1, path b); [10] and Ahmar et al, [11a] Brummond et al [11b] and Mukai et al [11c] have reported various approaches employing allenic reactions of the Pauson-Khand type (Scheme 1, path c). [12] Strategies based on the cyclization of acyclic dienynes, mediated [13a] or catalyzed [13b] by metal carbenes, have also been reported (Scheme 1, paths d and e).…”

mentioning

confidence: 99%

Tandem Brønsted Acid Promoted and Nazarov Carbocyclizations of Enyne Acetals to Hydroazulenones

et al. 2012

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Intramolecular [3+4] allyl cation cycloaddition: Novel route to hydroazulenes

Cited by 43 publications

References 30 publications

Correlation of Hydrolysis and Desilylation of 2‐[(Trimethylsilyl)methyl]acrylate Derivatives in Aqueous Alkali Solutions

Correlation of Hydrolysis and Desilylation of 2‐[(Trimethylsilyl)methyl]acrylate Derivatives in Aqueous Alkali Solutions

Stereoselective and Modular Assembly Method for Heterocycle‐Fused Daucane Sesquiterpenoids

Tandem Brønsted Acid Promoted and Nazarov Carbocyclizations of Enyne Acetals to Hydroazulenones

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