Bismuth(III) Reagents in Steroid and Terpene Chemistry

Salvador, Jorge A. R.; Silvestre, Samuel; Pinto, Rui M. A.

doi:10.3390/molecules16042884

Cited by 20 publications

(9 citation statements)

References 110 publications

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“…Indeed, a higher yield was only reported for the use of heteropoly acids (82% yield of dihydrocarvone 4 with 0.1 mol% catalyst loading) [34] as well as for the stoichiometric use of LiClO 4 (90% yield) [33]. The success of Bi(OTf) 3 is in good agreement with other results published in the literature, as the application of Bismuth was already shown to be efficient in several chemical transformations of terpenes, such as oxidation or acylation of alcohols, Wagner-Meerwein rearrangements and others [38], as well as in epoxide rearrangements of aromatic substrates [39]. Moreover, other triflates have been shown to be active in the Meinwald rearrangement, e.g.…”

Section: Results and Discussion (A) Optimization Of The Catalytic Reaction Conditionssupporting

confidence: 82%

Sustainable catalytic rearrangement of terpene-derived epoxides: towards bio-based biscarbonyl monomers

Löser

Rauthe

Meier

et al. 2020

Phil. Trans. R. Soc. A.

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Seeking a sustainable and selective approach for terpene modification, a catalyst deconvolution approach was applied to the Meinwald rearrangement of (+)-limonene oxide as a model substrate to yield dihydrocarvone. In order to identify the most suitable catalyst and reaction conditions, different Lewis acids were evaluated. Bismuth triflate proved to be the most active catalyst under mild reaction conditions, with a low catalyst loading (1 mol%) and a relatively short reaction time (3 h). The optimized reaction conditions were subsequently transferred to other terpene-based epoxides, yielding different bio-based biscarbonyl structures, which constitute interesting and valuable substances, e.g. for polymer synthesis or as fragrances. Monoepoxides derived from ( R )-(−)-carvone and (+)-dihydrocarvone rearranged to the desired products with high selectivities and yields. γ-Terpinene dioxide could be transformed in a double rearrangement to the respective biscarbonyl in moderate yields. A better result was achieved for limonene dioxide after further adjustment of the protocol to reach acceptable yields with a low catalyst loading of 0.1 mol% using 2-methyl tetrahydrofuran as a sustainable solvent. Compared to many procedures described in the literature, this procedure represents a step towards an increased sustainability in terpene modification by considering several principles of Green Chemistry, such as renewable resources, catalysis and mild reaction conditions for elementary chemical transformations. This article is part of a discussion meeting issue ‘Science to enable the circular economy’.

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Section: Results and Discussion (A) Optimization Of The Catalytic Reaction Conditionssupporting

confidence: 82%

Sustainable catalytic rearrangement of terpene-derived epoxides: towards bio-based biscarbonyl monomers

Löser

Rauthe

Meier

et al. 2020

Phil. Trans. R. Soc. A.

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“…Among the possible Lewis acidic metal centers in catalysis, the last two decades have witnessed a rising interest in the use of bismuth. Indeed, bismuth is cheap and low-toxic and therefore the implementation of catalytic processes based on this metal are an active task of research in green chemistry [73][74][75][76].…”

Section: Bismuth-based Systemsmentioning

confidence: 99%

Metal Complexes Bearing Sulfur-Containing Ligands as Catalysts in the Reaction of CO2 with Epoxides

et al. 2020

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Coupling of CO2 with epoxides is a green emerging alternative for the synthesis of cyclic organic carbonates (COC) and aliphatic polycarbonates (APC). The scope of this work is to provide a comprehensive overview of metal complexes having sulfur-containing ligands as homogeneous catalytic systems able to efficiently promote this transformation with a concise discussion of the most significant results. The crucial role of sulfur as the hemilabile ligand and its influence on the catalytic activity are highlighted as well.

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“…In the conclusion of the above-mentioned review, Zorn declares that in spite of 40 years research, an industrially feasible synthesis process still remains to be established, in order to replace the traditional citrus pulp/peel extraction. The chemical synthesis approaches for this transformation do work in high yield, but rely on stoichiometric amounts of hazardous substances such as chromates 39 or metal/peroxide auxiliaries, [40][41][42] complicating uses of the processes for generation of 10 for foodapplications Even though autoxidation of 9 (i.e. direct oxidation with O2) is a very promising approach and has been mentioned as a possibility to synthesize 10, 31 it has not been explored extensively, possibly because of the tedious conditions in the original publication, such as the use of a solvent and initiator, and a low conversion after 90 h reaction time.…”

Section: Scheme 1 Autoxidation Of β-Pinene (1)mentioning

confidence: 99%

Olefin Autoxidation in Flow

Neuenschwander

Jensen

2014

Ind. Eng. Chem. Res.

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Handling hazardous multiphase reactions in flow brings not only safety advantages but also significantly improved performance, due to better mass transfer characteristics. In this report, we present a continuous microreactor setup, capable of performing olefin autoxidations with O2, under solvent-free and catalyst-free conditions. Owing to the transparent reactor design, consumption of O2 can be visually followed and exhaustion of the gas bubbles marks a clear end point along the channel length coordinate. Tracking the position of this end point enables measuring effective rate constants. The developed system was calibrated using the well-studied β-pinene substrate, and was subsequently applied to the synthetically interesting transformation of (+)-valencene to (+)-nootkatone. For the latter, a space-time yield was obtained that is at least three orders of magnitude larger than that realized with established biotechnology approaches.

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Bismuth(III) Reagents in Steroid and Terpene Chemistry

Cited by 20 publications

References 110 publications

Sustainable catalytic rearrangement of terpene-derived epoxides: towards bio-based biscarbonyl monomers

Sustainable catalytic rearrangement of terpene-derived epoxides: towards bio-based biscarbonyl monomers

Metal Complexes Bearing Sulfur-Containing Ligands as Catalysts in the Reaction of CO2 with Epoxides

Olefin Autoxidation in Flow

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