Phosphine‐Mediated Reductive Condensation of γ‐Acyloxy Butynoates: A Diversity Oriented Strategy for the Construction of Substituted Furans.

Jung, Cheol‐Kyu; Wang, Jian‐Cheng; Krische, Michael J.

doi:10.1002/chin.200431107

Cited by 4 publications

(4 citation statements)

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“…Krische capitalized on this strategy by generating the highly reactive allenoate in situ, through a Wittig-like process, for annulation leading to functionalized furans. 787 Based on the proposed mechanism provided by Krische (Pathway A), the reaction proceeds through an allenoate intermediate (Scheme 691). Immediately after the allenoate intermediate is formed, nucleophilic addition of the phosphine occurs.…”

Section: Chemical Reviewsmentioning

confidence: 99%

Phosphine Organocatalysis

et al. 2018

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The hallmark of nucleophilic phosphine catalysis is the initial nucleophilic addition of a phosphine to an electrophilic starting material, producing a reactive zwitterionic intermediate, generally under mild conditions. In this Review, we classify nucleophilic phosphine catalysis reactions in terms of their electrophilic components. In the majority of cases, these electrophiles possess carbon–carbon multiple bonds: alkenes (section 2), allenes (section 3), alkynes (section 4), and Morita–Baylis–Hillman (MBH) alcohol derivatives (MBHADs; section 5). Within each of these sections, the reactions are compiled based on the nature of the second starting material—nucleophiles, dinucleophiles, electrophiles, and electrophile–nucleophiles. Nucleophilic phosphine catalysis reactions that occur via the initial addition to starting materials that do not possess carbon–carbon multiple bonds are collated in section 6. Although not catalytic in the phosphine, the formation of ylides through the nucleophilic addition of phosphines to carbon–carbon multiple bond–containing compounds is intimately related to the catalysis and is discussed in section 7. Finally, section 8 compiles miscellaneous topics, including annulations of the Hüisgen zwitterion, phosphine-mediated reductions, iminophosphorane organocatalysis, and catalytic variants of classical phosphine oxide–generating reactions.

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Section: Chemical Reviewsmentioning

confidence: 99%

Phosphine Organocatalysis

et al. 2018

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“…1 H NMR (500 MHz, CDCl 3 ) δ 8.02−7.94 (m, 2H), 7.46−7.37 (m, 4H), 6.85 (d, J = 1.9 Hz, 1H), 4.30 (q, J = 7.1 Hz, 2H), 1.34 (t, J = 7.1 Hz, 3H). 13 24 Ethyl 2-Phenyl-1H-pyrrole-3-carboxylate (31). A 5 mL flask equipped with a stirrer bar was charged with ethyl 5-ethoxy-2-phenyl-4,5-dihydrofuran-3-carboxylate (14a) (25 mg, 0.09 mmol), ammonium acetate (21 mg, 0.27 mmol, 3 equiv), molecular sieves 3 Å, and three drops of acetic acid followed by the addition of toluene (3 mL).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

A Visible Light Ru-Catalyzed Photoredox Access to Substituted Dihydrofurans

2022

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An efficient, visible light Ru(bpy) 3 Cl 2 -catalyzed method for the preparation of 2,3-dihydrofurans is reported. This approach employs 2-bromoketoesters as radical precursors and alkyl enol ethers as acceptors. The photoredox cycle furnishes an oxonium ion that is captured by an internal nucleophile to render the corresponding dihydrofurans. Moreover, the obtained products contain a versatile acetal moiety at C-2, allowing its transformation into a diverse variety of heteroaromatic and nonaromatic compounds. This method could serve as an important tool in the synthesis of complex tetrahydro-and dihydrofurans as well as heteroaromatic structures.Article pubs.acs.org/joc

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“…24 Krische reported yet another remarkable phosphinemediated heterocyclic construction in the reductive condensation of γ-acyloxy butynoates to deliver substituted furans (Scheme 15). 25 Because the starting butynoates are easily obtained by the addition of ethyl propiolate to aldehydes followed by acylation, this method represents a powerful diversity-oriented protocol for the convergent synthesis of furans.…”

Section: Nucleophilic Catalysismentioning

confidence: 99%