Cycloaddition routes to tricyclo[5.4.01,7.02,9]undecanes: a direct total synthesis of (+)-longifolene via an intramolecular Diels-Alder strategy

Lei, Bo; Fallis, Alex G.

doi:10.1021/jo00060a039

Cited by 37 publications

(13 citation statements)

References 4 publications

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“…Obtained as a pale yellow oil; [␣] D , IR, MS, 1 H and 13 C NMR identical with literature data (Lei and Fallis, 1993) and with an authentic standard.…”

Section: Longifolene (1)supporting

confidence: 53%

Antimycobacterial terpenoids from Juniperus communis L. (Cuppressaceae)

Gordien

Gray

Franzblau

et al. 2009

Journal of Ethnopharmacology

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“…Obtained as a pale yellow oil; [␣] D , IR, MS, 1 H and 13 C NMR identical with literature data (Lei and Fallis, 1993) and with an authentic standard.…”

Section: Longifolene (1)supporting

confidence: 53%

Antimycobacterial terpenoids from Juniperus communis L. (Cuppressaceae)

Gordien

Gray

Franzblau

et al. 2009

Journal of Ethnopharmacology

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“…[54] Scheme 19 Scheme 20 The cycloaddition reaction afforded 10% of the cycloadduct 62 after 24 h at reflux in toluene, while decomposition predominated at higher temperatures. When the triene was heated in a sealed glass vessel in a modified microwave oven, however, the adduct was obtained in 92% yield.…”

Section: Applications In the Synthesis Of Natural Productsmentioning

confidence: 99%

Cycloadditions under Microwave Irradiation Conditions: Methods and Applications

et al. 2000

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Microwave irradiation has been applied with success to cycloaddition reactions. The special characteristics of such irradiation entails the use of new methodologies, including equipment, glassware, solvents, and solid supports. All of these aspects are described in this review. Under classical heating conditions, these reactions usually require long reaction times, high temperatures, and/or Lewis acid catalysts, resulting in partial or total decomposition of sensitive compounds. This is a particularly significant problem in the synthesis of natural products. These problems have been conveniently overcome by the use of microwave irradiation. The short reaction time associated with microwave activation avoids decomposition of reagents and products, and prevents polymerization of the diene or dienophile. Heterocyclic compounds have been synthesized by cycloaddition reactions, or have been observed to react as dienes and dipoles under microwave irradiation conditions. Even those heterocyclic systems that are very reluctant to participate in cycloaddition reactions, such as pyrazoles, can be induced to react under microwave irradiation conditions. The application of this method to the chemistry of [60]fullerene has permitted derivatization of this system while avoiding the problems of polycycloaddition and cycloreversion. In most cases, spectacular accelerations and great improvements in yields and reaction conditions are observed. Finally, in some cases, changes in the chemo‐, regio‐, or stereoselectivity have been observed. These changes have been connected with the absolute hardness of the transition state, with the harder state being favored under microwave irradiation conditions. Microwave chemistry thus opens new possibilities for modifying the result of competitive reactions by considering the relative hardness of the transition states.

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“…Its unusual topology inspired many organic chemists and several superb total syntheses have been published. The approach of A.G. Fallis et al [28] starts from an epoxyfulvene that was converted into an unsaturated lactone via a four-step sequence including a resolution with (-)-menthol chloroformate and a condensation with the anion derived from methyl 3-methylcrotonate. The cyclopropane ring was regioselectively cleaved applying BF 3 × Et 2 O in methanol, affording a rapidly equilibrating mixture of substituted cyclopentadiene lactone isomers, due to the facile 1,5-sigmatropic rearrangement.…”

Section: Total Synthesis Of Various Classes Of Natural Productsmentioning

confidence: 99%