Synthetic studies on pyrrolizidine alkaloids. 1. (.+-.)-Heliotridine and (.+-.)-retronecine via intramolecular dienophile transfer

Keck, Gary E.; Nickell, D. G.

doi:10.1021/ja00530a058

Cited by 63 publications

(13 citation statements)

References 3 publications

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“…Changes in temperature generally had little effect, although carrying out the reaction in refluxing benzene (entry 4) improved the overall yield at the expense of cis selectivity. The latter conditions are similar to those employed in the dienophile transfer technique reported by Keck and Nickell, 8 which gave very similar results. More polar solvents (entries 5-7) afforded better yields, but the reaction was not selective.…”

supporting

confidence: 72%

Asymmetric synthesis of (+)-loline

2000

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supporting

confidence: 72%

Asymmetric synthesis of (+)-loline

2000

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“…[198] Representative compounds of this class of alkaloids that have been synthesized by using an intramolecular acylnitroso HDA strategy include swainsonine (196) and its derivatives, [199,200] fasicularin (197) and lepadiformine (198), [201] and other indolizidine alkaloids ( Figure 13). [187,189,199,[202][203][204][205][206][207][208][209] The synthesis of a particularly interesting member of the pyrrolidizine class of alkaloids, (+)-loline (202) was achieved by using an intramolecular acylnitroso HDA strategy (Scheme 37). [210,211] Hydroxamic acid 199 was oxidized to yield the oxazine 200.…”

Section: Indolidizine and Pyrrolidizine Alkaloidsmentioning

confidence: 99%

The Nitrosocarbonyl Hetero‐Diels–Alder Reaction as a Useful Tool for Organic Syntheses

Bodnar¹,

2011

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Organic transformations that result in the formation of multiple covalent bonds within the same reaction are some of the most powerful tools in synthetic organic chemistry. Nitrosocarbonyl hetero-Diels–Alder (HDA) reactions allow for the simultaneous stereospecific introduction of carbon–nitrogen and carbon–oxygen bonds in one synthetic step, and provide direct access to 3,6-dihydro-1,2-oxazines. This Review describes the development of the nitrosocarbonyl HDA reaction and the utility of the resulting oxazine ring in the synthesis of a variety of important, biologically active molecules.

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“…Thermolysis of the substituted cycloadducts allowed performance of ene reactions as intramolecular processes affording unsaturated pyrrolidinones in quantitative yields as shown in Scheme . The mild conditions of the thermal generation of functionalized NCs make the protocol particularly attractive for employment in natural products synthesis, such as the case of the total synthesis of (±)-perhydrohistrionicotoxin via an intramolecular ene reaction used for the construction of the spirocyclic skeleton of this natural product …”

Section: Nitrosocarbonyl Generation Methodsmentioning

confidence: 99%

“…These new substrates were thermally submitted to intramolecular ene processes affording unsaturated pyrrolidinones 13 in quantitative yields (Scheme ). The mild conditions of the processes (benzene at reflux, 5 h) make them particularly attractive for employment in natural products synthesis. , …”

Section: Nitrosocarbonyl Generation Methodsmentioning

confidence: 99%

Generation and Trapping of Nitrosocarbonyl Intermediates

Memeo

Quadrelli

2017

Chem. Rev.

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The nitrosocarbonyls (R-CONO) are highly reactive species and remarkable intermediates toward different synthetic targets. This review will cover a research area whose impact in current organic synthesis is constantly increasing in the chemical community. This review represents the first and comprehensive picture on the generation and trapping of nitrosocarbonyls and is solidly built on more than 380 papers. Six different classes of key starting materials such as hydroxamic acids, N-hydroxy carbamates, N-hydroxyureas, nitrile oxides, and 1,2,4-oxadiazole-4-oxides were highlighted. The content of the review surveys all the methods to generate the nitrosocarbonyls through different approaches (oxidative, thermal, photochemical, catalytic, aerobic, and the less common ones) in the light of efficiency, yields, and mildness. The most successful trapping agents employed to catch these fleeting intermediates are reviewed, exploiting their superior dienophilic, enophilic, and electrophilic power. The work is completed by paragraphs dedicated to the detection of the intermediates, theoretical studies, and insights about the challenges and future directions for the field.

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Synthetic studies on pyrrolizidine alkaloids. 1. (.+-.)-Heliotridine and (.+-.)-retronecine via intramolecular dienophile transfer

Cited by 63 publications

References 3 publications

Asymmetric synthesis of (+)-loline

Asymmetric synthesis of (+)-loline

The Nitrosocarbonyl Hetero‐Diels–Alder Reaction as a Useful Tool for Organic Syntheses

Generation and Trapping of Nitrosocarbonyl Intermediates

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