Organocatalytic Stereospecific Appel Reaction

Tönjes, Jan; Kell, Lukas; Werner, Thomas

doi:10.1021/acs.orglett.3c03463

Cited by 4 publications

(1 citation statement)

References 32 publications

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“…The use of hexamethylphosphetane oxide 3a afforded the desired trisubstituted furan 4a in a satisfactory yield of 71% (Table , entry 1). This highly active catalyst was used in various transformations in recent years. ,− In the presence of the more sterically demanding phosphine oxide 3b , no product formation was observed (entry 2). Surprisingly, the less sterically demanding tetramethylphospetane oxide 3c , which was recently introduced by the group of Radosevich, gave the product 4a in only 24% yield (entry 3). , Several other phosphine oxides 3d – 3g were employed as catalysts.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Trisubstituted Furans from Activated Alkenes by P(III)/P(V) Redox Cycling Catalysis

Tönjes,

Medvarić,

Werner

2024

J. Org. Chem.

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The organocatalytic formation of an underrepresented family of trisubstituted and tetrasubstituted furans from activated alkenes and acyl chlorides is reported. In a reaction sequence based on P(III)/P(V) redox cycling catalysis, the cyclic phosphine catalysts react with diacylethenes or acyl acrylates in Michael addition, followed by acylation and either an intramolecular Wittig reaction or a ring closure reaction, liberating the furans. The formed phosphine oxides are reduced in situ by phenylsilane as a terminal reductant. In the first step, 12 diacylethenes were converted to the respective trisubstituted furans. The reaction of acyl acrylates showed a surprising, catalyst-dependent alternate reaction forming tetrasubstituted furans. Two additional methods were developed, giving 14 trisubstituted furans using a phospholene catalyst and an additional 6 tetrasubstituted furans using a phosphetane catalyst. This encompassed 19 newly described compounds.

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Section: Resultsmentioning

confidence: 99%

Synthesis of Trisubstituted Furans from Activated Alkenes by P(III)/P(V) Redox Cycling Catalysis

Tönjes,

Medvarić,

Werner

2024

J. Org. Chem.

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Auto‐Optimized Electro‐Flow Reactor Platform for the in‐situ Reduction of P(V) Oxide to P(III) and Their Application

Purwa,

Chandrakanth,

Rana

et al. 2024

Chemistry An Asian Journal

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Trivalent phosphine catalysis is mostly utilized to activate the carbon‐carbon multiple bonds to form carbanion intermediate species and highly sensitive to certain variables. Random manual multi‐variables are critical for understanding the batch disabled regeneration of trivalent phosphine chemistry. We need the artificial intelligence‐based system which can change the variable based on previously conducted failed experiment. Herein, we report an auto‐optimized electro‐micro‐flow reactor platform for the in‐situ reduction of stable P(V) oxide to sensitive P(III) and further utilized for Corey‐Fuchs reaction.

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Moderation of the Electronic Structure of Phosphamides to Execute the Catalytic Appel Reaction Bypassing Phosphine

Kumari,

Jagadeesh,

Galav

et al. 2024

J. Org. Chem.

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A set of structurally analogous, albeit electronically distinct, phosphamides (1aa-10aa) is prepared, and the effect of the electronic amendment due to p-substitution has been tested for the conversion of alcohols to halides via the Appel reaction. The −OMe-substituted diphosphamide (8aa) remains the most active, providing ∼96% conversion of alcohols to halides with a TON of 11 in moderate reaction conditions with a large substrate scope. Halide formation follows a pseudo-first-order rate with a constant rate (k obs ) of 7.13 × 10 −5 s −1 . Temp-dependent kinetics and Eyring analyses reveal the activation parameters ΔH ‡ of 28.95 (±1.6) kcal mol −1 , ΔS ‡ of −70.02 (±0.4) cal K −1 mol −1 , and ΔG ‡ 298 of 49.81 (±1.2) kcal mol −1 . The deuterium labeling study highlights the O−H dissociation of the alcohol as the rate-determining step, while the Hammett analysis with p-substituted benzyl alcohols indicates a positive charge accumulation at the phosphorus center during the Appel reaction. The HOMO−LUMO energy and NPA analyses show that p−OMe substitutions in 8aa make the "P�O" bond more ionic and corresponding aminophosphine is nucleophilic, which are favorable for the Appel reaction. In situ detection of the Appel salt, [R 3 PX]CX 3 and alkoxy phosphonium cation [R 3 POR]X, validates the reaction pathway mediated by the phosphamides.

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Organocatalytic Stereospecific Appel Reaction

Cited by 4 publications

References 32 publications

Synthesis of Trisubstituted Furans from Activated Alkenes by P(III)/P(V) Redox Cycling Catalysis

Synthesis of Trisubstituted Furans from Activated Alkenes by P(III)/P(V) Redox Cycling Catalysis

Auto‐Optimized Electro‐Flow Reactor Platform for the in‐situ Reduction of P(V) Oxide to P(III) and Their Application

Moderation of the Electronic Structure of Phosphamides to Execute the Catalytic Appel Reaction Bypassing Phosphine

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