Diensynthesen unter hohem druck

Jones, William H.; Mangold, Dietrich; Plieninger, Hans

doi:10.1016/s0040-4020(01)93238-7

Cited by 35 publications

(11 citation statements)

References 7 publications

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“…By distillation 2.12 g (50%) of pure product was obtained as a clear, water-white liquid: bp 69-70 °C (14 Torr); NMR b 4.78 (t, J = 5 Hz. 1.0CH0CH2CH3), 4.20 (s, 1, =CH), 3.60 (m, 2, OCHsCHs), 1.67 is, 3, =CCH:J), 1.54 (d, J = 5 Hz, 2, CHCH2), 1.16 (t, J = 7 Hz, 3, OCH2CH3), 1.03 (s, 3, CCH3), 0.98 (s, 3, CCH3); IR 3020, 1660, 787 cm"'1; MS m/e (rel intensity) 170 (M+, 17), 155 (21), 125 (12), 109 (17), 85 (16), 83 (28), 81 (11), 73 (11), 72 (100), 44 (58), 43 (97).…”

Section: Methodsmentioning

confidence: 99%

“…Although the utility of very high pressure (8000-20 000 atm) in organic synthesis is conceptually obvious, such a parameter has not, in fact, been adequately explored. [9][10][11] When reactions are performed at these very high pressures, the system does not follow the ideal rate equation since the V*, itself, is pressure dependent. However, for cycloaddition reactions with a -* of ~25 ml/mol, the rule of thumb, based upon experimental findings, is that above 1000 atm pressure (1 kbar), every kbar increase doubles the rate of the reaction.7 Thus, the rate enhancement closely follows the general temperature dependency and indicates that a cycloaddition which occurs at 100 °C at atmospheric pressure could be achieved at 20 °C with a pressure of 9-10 kbar.…”

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confidence: 99%

“…Results and Discussion (fi)-(-)-[3]Chochin (10) and (R,R)-(-)- [4]Chochin (11 ).5 Our general scheme for the preparation of optically active multilayered [2.2]paracyclophanes can be seen in Scheme I, which illustrates the synthetic route to the twoand three-layered [2.2]paracyclophanes, 10 and 11. (R)-(-)-4-Methyl[2.2]paracyclophane (l),6 whose absolute configuration had been determined, served as our starting material as well as a liaison compound relating the stereochemistry of the [2.2] paracyclophane series to that of our multilayered compounds. Acetylation of 1 with acetyl chloride and anhydrous aluminum chloride afforded the acetyl derivative 2, which was further converted by a haloform reaction into (R)-(-[-carboxylic acid (3a), mp 205-206 °C, [a]21D -224°.…”

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confidence: 99%

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Organic reactions at high pressure. Cycloadditions with enol and dienol derivatives

Dauben¹,

Krabbenhoft²

1977

J. Org. Chem.

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Cycloaddition reactions between 1-acetoxybutadiene and various monofunctionalized (CHO, COCH3, C O~C H Y , and CN) ethylenes (i.e., acrylic dienophiles) or propylenes (Le., crotonic dienophiles) under the influence of 15 000 atm pressure and room temperature have been. studied. With the acrylic dienophiles only the ortho-cis cycloadducts were obtained in fair to good yields; with the crotonic dienophiles only crotonaldehyde gave the desired cyclized product in 5% yield. The diminished reactivity of the crotonic dienophiles compared to their acrylic counterparts is ascribed to the combination of unfavorable steric and electronic effects brought about by the introduction of the @-methyl group. Similar results were found when 1-methoxybutadiene was employed as the diene component. No cycloaddition products were generated from ethyl vinyl ether and 1-carboalkoxybutadienes (Diels-Alder reactions with inverse electron demand) under the high pressure conditions. The utilization of high pressures (15 000-20 000 atm) and moderate temperatures (24-110 "C) provides a valuable synthetic technique in preparation of 2-alkoxy-3,4-dihydro-2H-pyrans from a,@-unsaturated aldehydes or ketones and vinyl ethers (heterodiene synthesis) since the high-pressure reactions can be conducted at temperatures substantially lower than those required when the reactions are carried out at atmospheric pressure. The steric and electronic effects of methyl substitution on the diene and/or dienophile are described.

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Organic reactions at high pressure. Cycloadditions with enol and dienol derivatives

Dauben¹,

Krabbenhoft²

1977

J. Org. Chem.

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“…More drastic temperature conditions are unfavorable for the yield of the target adduct, because the process is reversible. Only elevated temperature (100 °C) and pressure (10-12 kbar) make it possible to achieve 90% yield of the product (adduct of naphthalene with maleic anhydride) 6,7 The purpose of this work was to estimate the reactivity of simple arenes as dienes in the Diels-Alder reaction, and to use different ways of activation of reactants in this reaction.…”

Section: Introductionmentioning

confidence: 99%

Diels-Alder reaction between naphthalene and N-phenylmaleimide under ambient and high pressure conditions

Iskhakova¹,

Kiselev²,

Kashaeva³

et al. 2005

Arkivoc

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The rate and equilibrium constants for the Diels-Alder reactions between benzene and naphthalene as dienes and tetracyanoethylene, maleic anhydride and N-phenylmaleimide as dienophiles at 25 °С were estimated from empirical rule. The highest yield of the adduct was predicted for the reaction of naphthalene with N-phenylmaleimide. The time of adduct formation in 50% yield exceeds 30 years. The use of gallium chloride as a catalyst affords the exo-adduct for seven days at room temperature. The rate ((2±0.5)•10 -6 L mol -1 s -1 ) and equilibrium constants (5±2 L mol -1 ) of this reaction were determined. Under high pressure conditions (8 kbar) reaction occurs with formation of both stereo isomers at 100 °С during 80 hours.

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“…[1][2][3][4][5] If the planarity of the naphthalene is partially disrupted by bulky substituents or by incorporating the naphthalene moiety in a short-bridged cyclophane, then the feasibility of this reaction is likely to be increased. 6 Such a ring distortion occurs in the [5]-or [6]-aza-1,7-naphthalenophane systems.…”

Section: Introductionmentioning

confidence: 99%

Novel polycyclic Diels-Alder adducts from ring distorted 3-aza[5] and 3-aza[6] (1,7) naphthalenophanes

Bremner¹,

Jaturonrusmee²

2005

Arkivoc

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Dedicated to Professor Jim Coxon on the occasion of his 65th birthday. AbstractRing distorted 3-aza[5] and 3-aza [6](1,7)naphthalenophanes have been shown to undergo ready Diels-Alder cycloaddition reactions with 4-phenyl-1,2,4-triazoline-3,5-dione, tetracyanoethylene, 1,1-dicyanoethylene and 1,1-diethyl methylenemalonate to form new functionalized polycyclic heterocyclic derivatives. Addition was shown to occur selectively in each case in the less substituted aromatic ring of the naphthalene moiety.

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Diensynthesen unter hohem druck

Cited by 35 publications

References 7 publications

Organic reactions at high pressure. Cycloadditions with enol and dienol derivatives

Organic reactions at high pressure. Cycloadditions with enol and dienol derivatives

Diels-Alder reaction between naphthalene and N-phenylmaleimide under ambient and high pressure conditions

Novel polycyclic Diels-Alder adducts from ring distorted 3-aza[5] and 3-aza[6] (1,7) naphthalenophanes

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