Zur Diels‐Alder‐Reaktivität <i>s</i>‐<i>cis</i>‐fixierter 1,3‐Diene

Scharf, Hans‐Dieter; Plum, H.; Fleischhauer, Jörg; Schleker, Wolfgang

doi:10.1002/cber.19791120312

Cited by 57 publications

(15 citation statements)

References 47 publications

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“…As in the case of 1‐fluorobuta‐1,3‐dienes, 11 , the fluorodiene ( Z )‐ 13 is definitively less reactive than its ( E )‐isomer in the hetero‐Diels–Alder addition with SO 2 ; this is in agreement with predictions based on quantum calculations11 and as demonstrated for the hetero‐Diels–Alder additions of SO 2 to piperilenes 4a. Because of steric repulsions between the C−F and C−H groups (1,4‐interactions) in the s‐cis conformer of the ( Z )‐1‐fluorobutadiene moiety, the 1,4‐distance is increased and this retards the cycloaddition 20. At −20 °C, ( Z )‐ 13 added slowly to SO 2 with preferred formation of trans ‐ 30 .…”

Section: Introductionsupporting

confidence: 88%

The Hetero-Diels-Alder Addition of Sulfur Dioxide to 1-Fluorobuta-1,3-dienes: The Sofa Conformations Preferred by 6-Fluorosultines (6-Fluoro-3,6-dihydro-1,2-oxathiin-2-oxides) Enjoy Enthalpic and Conformational Anomeric Effects

et al. 2002

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The reactivity of (E)‐ and (Z)‐1‐fluorobuta‐1,3‐diene ((E)‐ and (Z)‐11), 2‐fluorobutadiene (12), (E)‐ and (Z)‐1‐(fluoromethylidene)‐2‐methylidenecyclohexane ((E)‐ and (Z)‐13) toward SO2 has been explored and compared with that of (Z)‐ and (E)‐1‐(fluoromethylidene)‐2‐methylidene‐3,4‐dihydronaphthalene ((Z)‐8 and (E)‐8). In agreement with quantum calculations, 12 is unreactive toward SO2 (no cycloaddition, only polymerization), whereas (E)‐1‐fluoro‐1,3‐dienes react more rapidly than their (Z)‐isomers to give the corresponding 6‐fluorosultines following the endo (Alder rule) mode of hetero‐Diels–Alder addition. No sulfolene has been observed following the cheletropic mode of addition with the fluorodienes, in contrast to other substituted dienes. In agreement with the calculations, cis‐2‐fluoro‐3,4‐oxathiabenzobicyclo[4.4.0]dec‐1(6),9‐diene‐4‐oxide (cis‐9, the sultine obtained by SO2 addition to (Z)‐8 under conditions of kinetic control) adopts a sofa conformation with the oxygen atom of the ring lying in the average plane of the four carbon atoms of its sultine moiety when it is in the crystalline state at −100 °C. A similar sofa conformation was found for its trans‐isomer, trans‐9, obtained by isomerization of cis‐9 or by hetero‐Diels–Alder addition of SO2 to (E)‐8. Experiments (equilibrium constant for hetero‐Diels–Alder additions, bond lengths, and bond angles in crystalline fluorosultines cis‐9 and trans‐9) and high‐level quantum calculations on cis‐ and trans‐6‐fluoro‐3,6‐dihydro‐1,2‐oxathiin‐2‐oxide (cis‐ and trans‐20) confirm the existence of a stabilizing, enthalpic, anomeric (gem‐disubstitution by sulfinyloxy and fluoro groups) effect, which is interpreted in terms of (lone pair) n(O1)→σ*(C−F) hyperconjugative interactions. This effect is strongest in the sofa conformers with a gauche arrangement of the σ(O1,S2) and σ(C6,F) bonds. The calculations suggest also that n(O1)→σ*(S2,O2′), π*(S=O), and n(S2)→σ*(O1,C6) interactions intervene and affect the relative stability of the conformers (sofa, boat, pseudo‐chair) found for 6‐fluorosultines cis‐ and trans‐20.

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Section: Introductionsupporting

confidence: 88%

The Hetero-Diels-Alder Addition of Sulfur Dioxide to 1-Fluorobuta-1,3-dienes: The Sofa Conformations Preferred by 6-Fluorosultines (6-Fluoro-3,6-dihydro-1,2-oxathiin-2-oxides) Enjoy Enthalpic and Conformational Anomeric Effects

et al. 2002

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“…Treatment of compound 19 with BuLi at --100 OC resulted in Reagents and conditions: i, BuLi (4 mol equiv. ), 1 : 1 TMEDA-hexane, -45 to 0 "C, then ClSiMe, (4.2 mol equiv.…”

Section: Synthesis Of P-trimethylsilyl-gem-dihalogenocyclopropanesmentioning

confidence: 99%

Generation and solution-phase behaviour of some 2-halogeno-1,3-ring-fused cyclopropenes

Banwell¹,

Corbett²,

Gulbis³

et al. 1993

J. Chem. Soc., Perkin Trans. 1

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“…This latest advantage of the base catalysts is closely related to Green Chemistry and technology rules, what is very important in chemical synthesis. The most often used basic catalyst for double bond migration in Q CH 2 CH=CH 2 to Q CH=CHCH 3 ( Q =allyl O , aryl O , alkyl S , Ph S , Ph S ( O )‐, Ph S ( O 2 )‐ and other O ‐ and S ‐allyl compounds) is t ‐BuOK (most frequently in DMSO) . Recently, LDA in THF was also used for allyl ethers isomerization , .…”

Section: Introductionmentioning

confidence: 99%

Crown Ether Base: Highly Active, Regioselective and Reusable Catalytic Systems for Double Bond Migration in Allylic Compounds

et al. 2017

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The highly active, reusable and regioselective crown ethers bases catalytic systems, especially 15‐Crown‐5/NaOH, 18‐Crown‐6/KOH, dibenzo‐18‐Crown/6‐t‐BuOK, and 18‐Crown‐6/t‐BuOK, for double bond migration in various allyl and diallyl compounds have been presented. Allyl and/or diallyl: arenes and heteroarenes, ethers, acetal, sulfides, selenide, sulfoxides, imines, phosphine, and phosphine oxide were smoothly converted into their corresponding 1‐propenyl derivatives under very mild conditions. Some of the C,O‐ and O,S‐diallyl compounds were fully regioselectively isomerized to allyl‐(1‐propenyl) derivatives. An unprecedented and significant effect of increasing the reaction rate and shortening the quantitative reaction conversion time without decreasing the selectivity under ultrasound‐assisted conditions was observed. Various solvents, including low‐boiling point ones containing only C, H and/or O atoms, such as DMFL, DME, THF, Et2O, toluene, and 1,4‐dioxane, can be used instead of the most frequently used DMSO. Remarkably highly effective recycling of 18‐Crown‐6/t‐BuOK and dibenzo‐18‐Crown‐6‐t‐BuOK catalytic systems for isomerization of low‐boiling or high‐boiling point allyl compounds respectively and crown ethers from all examined catalytic systems was developed. The opportunity to effectively combine the double bond migration with in situ generation of nitrile oxide and finally 1,3‐DC‐cycloaddition into one pot variant synthesis of isoxazolines from Qallyl has also been announced.

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Zur Diels‐Alder‐Reaktivität s‐cis‐fixierter 1,3‐Diene

Cited by 57 publications

References 47 publications

The Hetero-Diels-Alder Addition of Sulfur Dioxide to 1-Fluorobuta-1,3-dienes: The Sofa Conformations Preferred by 6-Fluorosultines (6-Fluoro-3,6-dihydro-1,2-oxathiin-2-oxides) Enjoy Enthalpic and Conformational Anomeric Effects

The Hetero-Diels-Alder Addition of Sulfur Dioxide to 1-Fluorobuta-1,3-dienes: The Sofa Conformations Preferred by 6-Fluorosultines (6-Fluoro-3,6-dihydro-1,2-oxathiin-2-oxides) Enjoy Enthalpic and Conformational Anomeric Effects

Generation and solution-phase behaviour of some 2-halogeno-1,3-ring-fused cyclopropenes

Crown Ether Base: Highly Active, Regioselective and Reusable Catalytic Systems for Double Bond Migration in Allylic Compounds

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