Iron(III) Chloride Catalyzed Formation of 3,4-Dihydro-2<i>H</i>-pyrans from α-Alkylated 1,3-Dicarbonyls. Selective Synthesis of α- and β-Lapachone

Watson, Rebecca B.; Golonka, Alexander N.; Schindler, Corinna S.

doi:10.1021/acs.orglett.6b00254

Cited by 19 publications

(8 citation statements)

References 43 publications

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“…Existing reports to access this structural motif often utilize Brønsted or Lewis acid catalyzed [4 + 2]-cycloaddition reactions of o -alkynyl(oxo)-benzenes 5 with alkenes 6 , or isochromene acetals 8 with vinyl boronates 9 (Figure B) . We herein present a mild and efficient strategy for the synthesis of tetrahydronaphthalenes 4 which was inspired by mechanistic insights obtained during our previous studies toward the synthesis of 3,4-dihydro- 2H -pyrans 2 from aryl ketones 1 bearing α-carbonyl substituents . The corresponding α-arylated analogs of 1 exhibit divergent reactivity upon Brønsted or Lewis acid catalysis resulting in either the preferential formation of pyrans 3 or the exclusive formation of tetrahydronaphthalenes 4 depending on the choice of activation (Figure A).…”

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confidence: 99%

Iron-Catalyzed Synthesis of Tetrahydronaphthalenes via 3,4-Dihydro-2H-pyran Intermediates

Watson

Schindler

2017

Org. Lett.

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The development of an iron(III)-catalyzed synthetic strategy toward functionalized tetrahydronaphthalenes is described. This approach is characterized by its operational simplicity and is distinct from currently available procedures that rely on [4 + 2]-cycloadditions. Our strategy takes advantage of the divergent reactivity observed for simple aryl ketone precursors to gain exclusive access to tetrahydronaphthalene products (23 examples). Detailed mechanistic investigations identified pyrans as reactive intermediates that afford the desired tetrahydronaphthalenes in high yields upon iron(III)-catalyzed Friedel-Crafts alkylation.

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confidence: 99%

Iron-Catalyzed Synthesis of Tetrahydronaphthalenes via 3,4-Dihydro-2H-pyran Intermediates

Watson

Schindler

2017

Org. Lett.

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“…They have unsaturated side chains with one more carbon than the COM δ,ϵ‐unsaturated ketone substrates in Scheme 3b. The γ,δ‐unsaturated ketone substrates in Scheme 3c can be considered one CH 2 truncated versions of the COM substrates [29] . The alkenyl and alkynyl [30] keto subtrates in Scheme 3d and e bear slightly different unsaturated side chains but can be considered synthetic equivalents of the ones in Scheme 3c.…”

Section: Resultsmentioning

confidence: 99%

Hydrogen Bonding Networks Enable Brønsted Acid‐Catalyzed Carbonyl‐Olefin Metathesis**

Pei

Koenigs

et al. 2022

Angewandte Chemie

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Synthetic chemists have learned to mimic nature in using hydrogen bonds and other weak interactions to dictate the spatial arrangement of reaction substrates and to stabilize transition states to enable highly efficient and selective reactions. The activation of a catalyst molecule itself by hydrogen‐bonding networks, in order to enhance its catalytic activity to achieve a desired reaction outcome, is less explored in organic synthesis, despite being a commonly found phenomenon in nature. Herein, we show our investigation into this underexplored area by studying the promotion of carbonyl‐olefin metathesis reactions by hydrogen‐bonding‐assisted Brønsted acid catalysis, using hexafluoroisopropanol (HFIP) solvent in combination with para‐toluenesulfonic acid (pTSA). Our experimental and computational mechanistic studies reveal not only an interesting role of HFIP solvent in assisting pTSA Brønsted acid catalyst, but also insightful knowledge about the current limitations of the carbonyl‐olefin metathesis reaction.

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“…Initially, for instance, it can be observed that lapachones present interesting π‐conjugated chromophoric units; relatively simple changes in their electronic structures involve a colour change that can be used to monitor their reaction (Scheme 30). [15a] …”

Section: Photophysical Propertiesmentioning

confidence: 99%

Imidazoles and Oxazoles from Lapachones and Phenanthrene‐9,10‐dione: A Journey through their Synthesis, Biological Studies, and Optical Applications

Dias

Paz

Nunes

et al. 2021

The Chemical Record

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Diverse structural frameworks are found in natural compounds and are well known for their chemical and biological properties; such compounds include the imidazoles and oxazoles. Researchers worldwide are continually working on the development of methods for synthesizing new molecules bearing these basic moiety and evaluating their properties and applications. To expand the knowledge related to azoles, this review summarizes important examples of imidazole and oxazole derivatives from 1,2-dicarbonyl compounds, such as lapachones and phenanthrene-9,10-diones, not only regarding their synthesis and biological applications but also their photophysical properties and uses. The data concerning the latter are particularly scarce in the literature, which leads to underestimation of the potential applications that can be envisaged for these compounds.

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Iron(III) Chloride Catalyzed Formation of 3,4-Dihydro-2H-pyrans from α-Alkylated 1,3-Dicarbonyls. Selective Synthesis of α- and β-Lapachone

Cited by 19 publications

References 43 publications

Iron-Catalyzed Synthesis of Tetrahydronaphthalenes via 3,4-Dihydro-2H-pyran Intermediates

Iron-Catalyzed Synthesis of Tetrahydronaphthalenes via 3,4-Dihydro-2H-pyran Intermediates

Hydrogen Bonding Networks Enable Brønsted Acid‐Catalyzed Carbonyl‐Olefin Metathesis**

Imidazoles and Oxazoles from Lapachones and Phenanthrene‐9,10‐dione: A Journey through their Synthesis, Biological Studies, and Optical Applications

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