<i>Diels‐Alder</i> reaction of 6‐demethoxy‐β‐dihydrothebaine with methyl vinyl ketone using microwave heating; preparation and pharmacology of 3‐hydroxy‐α,α, 17‐trimethyl‐6β,14β‐ethenomorphinan‐7β‐methanol, a novel deoxygenated diprenorphine analogue (chemistry of opium alkaloids, part XXV

Linders, J. T. M.; Kokje, J. P.; Overhand, M.; Lie, T. S.; Maat, L.

doi:10.1002/recl.19881070610

Cited by 46 publications

(15 citation statements)

References 22 publications

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“…Most workers conduct reactions in solution in sealed vessels (Giguere et al 1986, Baghurst et al 1989) and consider acceleration to be due to the high temperatures and pressures generated when solvents with high dielectric constants absorb microwave energy. However, some studies have reported enhanced reaction rates for syntheses conducted in open systems in microwave ovens compared to equivalent conventional heating (Linders et al 1988, Gutierrez et al 1989). …”

Section: Introductionmentioning

confidence: 98%

The effect of microwave energy on specific migration from food contact plastics

Jickells

Gramshaw

Castle

et al. 1992

Food Additives and Contaminants

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Experiments have been carried out with (a) microwave treatment of plastics followed by migration testing using the food simulant, olive oil, and (b) microwave treatment of plastics in direct contact with an organic extractant (iso-octane). In neither of these complementary approaches was there evidence of any difference in migration from plastics that had been microwave-treated compared with plastics that had received an equivalent thermal treatment. Five plastics commonly employed in microwave applications were tested and oligomers, plasticizer, antioxidant and volatile contaminants were monitored as representatives of typical migration species.

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Section: Introductionmentioning

confidence: 98%

The effect of microwave energy on specific migration from food contact plastics

Jickells

Gramshaw

Castle

et al. 1992

Food Additives and Contaminants

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“…Use of MW irradiation as an energy source is crucial to performing the reaction and avoiding decomposition or dimerization of the starting pyrazole, which are observed in the absence of MW irradiation. A similar conclusion was drawn during an examination of the DA reaction of 6-demethoxy-β-dihydrothebaine with methyl vinyl ketone using the action of MW irradiation [210]. When performed under conventional heating conditions, extensive polymerization of the dienophile was observed whereas the reaction was much cleaner under MW activation [Eq.…”

Section: Some Illustrative Examples Of the Effects On Selectivitymentioning

confidence: 60%

Nonthermal Effects of Microwaves in Organic Synthesis

Perreux¹,

Loupy²,

Petit³

2012

Microwaves in Organic Synthesis

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“…Linders et al [73] studied the Diels±Alder reaction of 6-demethoxy-b-dihydrothebaine with an excess of methyl vinyl ketone (used both as reactant and solvent), which gives a mixture of two isomeric adducts. When the reaction was performed using classical heating extensive polymerization occurred, whereas much less polymeric material was formed when the reaction was performed in a modified MW oven under reflux conditions, resulting in a 32 % yield of the isomeric mixture of the mixture of adducts.…”

Section: Selectivity In Mw-assisted Reactionsmentioning

confidence: 99%

Organic Synthesis Using Microwaves in Homogeneous Media

Gedye

2002

Microwaves in Organic Synthesis

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Although the ability of microwaves (MW) to heat water and other polar materials has been known for half a century or more, it was not until 1986 that two groups of researchers independently reported the application of MW heating to organic synthesis. Gedye et al. [1] found that several organic reactions in polar solvents could be performed rapidly and conveniently in closed Teflon vessels in a domestic MW oven. These reactions included the hydrolysis of amides and esters to carboxylic acids, esterification of carboxylic acids with alcohols, oxidation of alkyl benzenes to aromatic carboxylic acids and the conversion of alkyl halides to ethers.Most of these reactions occurred much faster using MW irradiation (at increased pressure and temperature) than under conventional heating (ambient pressure, reflux), with rate enhancements ranging from 5 to 1200 times.Shortly after these results were published, Giguere and coworkers reported dramatic reductions in reaction times in other MW-assisted syntheses, including Diels± Alder, Claisen rearrangements and ene reactions [2]. These reactions were also performed at elevated pressures, but sealed glass vessels (inside a bath packed with vermiculite) were used rather than Teflon.It is to be noted that the reactions mentioned so far were performed under homogeneous conditions and, in most cases, using polar solvents, which are efficient absorbers of MW energy. Rate enhancements were attributed to the superheating of the solvent due to the elevated pressures generated in the closed vessels.During the 15 years since these reports, a large number of synthetic applications of MW in organic. synthesis have been reported and these have been summarized in a number of reviews [3±10].The use of dry media (solvent-free) conditions, in which the reactants are absorbed on inert solid supports, in MW-heated reactions, has received a considerable amount of attention recently and has been used in the synthesis of a wide range of compounds [11±16]. These reactions generally occur rapidly and the method avoids hazards, such as explosions, associated with reactions in solvents in sealed vessels in which high pressures may be generated. Also the removal of 115 Microwaves in Organic Synthesis. Edited by Andr Loupy

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Cited by 46 publications

References 22 publications

The effect of microwave energy on specific migration from food contact plastics

The effect of microwave energy on specific migration from food contact plastics

Nonthermal Effects of Microwaves in Organic Synthesis

Organic Synthesis Using Microwaves in Homogeneous Media

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