Stay positive: catalysis with 1,3,2-diazaphospholenes

Reed, John H.; Klett, Johannes; Steven, Craig; Cramer, Nicolai

doi:10.1039/d0qo00848f

Cited by 20 publications

(6 citation statements)

References 47 publications

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“…Building on our previous work 59 , we envisioned that diazaphospholenes of super hydricity 60 – 62 may provide a good chance to realize HDF of trifluoromethylalkenes via an S N 2’ path 63 . A preliminary attempt indicated that the reaction of α-trifluoromethyl-styrene 2a with diazaphospholene 1 primarily gave the hydrophosphination intermediate A .…”

Section: Resultsmentioning

confidence: 98%

Chemoselective catalytic hydrodefluorination of trifluoromethylalkenes towards mono-/gem-di-fluoroalkenes under metal-free conditions

2021

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Fluorine-containing moieties show significant effects in improving the properties of functional molecules. Consequently, efficient methods for installing them into target compounds are in great demand, especially those enabled by metal-free catalysis. Here we show a diazaphospholene-catalyzed hydrodefluorination of trifluoromethylalkenes to chemoselectively construct gem-difluoroalkenes and terminal monofluoroalkenes by simple adjustment of the reactant stoichiometry. This metal-free hydrodefluorination features mild reaction conditions, good group compatibility, and almost quantitative yields for both product types. Stoichiometric experiments indicated a stepwise mechanism: hydridic addition to fluoroalkenes and subsequent β-F elimination from hydrophosphination intermediates. Density functional theory calculations disclosed the origin of chemoselectivity, regioselectivity and stereoselectivity, suggesting an electron-donating effect of the alkene-terminal fluorine atom.

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Section: Resultsmentioning

confidence: 98%

Chemoselective catalytic hydrodefluorination of trifluoromethylalkenes towards mono-/gem-di-fluoroalkenes under metal-free conditions

2021

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“…This feature might be exploited further in the context of diazaphospholene chemistry for organocatalysis. [40] We also monitored the NMR-scale reaction of 1 with a 1.5 M stock solution of dimethylamine, which led to a mere 7 % conversion to 7 after a few minutes at room temperature with no further conversion observed over time. The combined experimental and computational data suggest that a high activation barrier for reaction between the amine substrate and the distorted P(III) center under the chosen conditions may be responsible for the observed lack of complete proton transfer in case of the latter reaction as well as for the formation of 6 as a minor equilibrium product.…”

Section: Synthesis Of P(iiimentioning

confidence: 99%

Geometrically Deformed and Conformationally Rigid Phosphorus Trisamides Featuring an Unsymmetrical Backbone

Beims,

Greven,

Schmidtmann

et al. 2023

Chemistry A European J

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Nonclassical P(III) centers have attracted much attention in recent years. Incorporating a P(III) center in a rigid bicyclic platform offers a particularly attractive way to invoke significant geometric distortion of the phosphorus atom that may in turn induce unusual reactivity. Although still relatively scarcely explored, phosphorus centers enforced in a non‐C3 symmetry have gained significant traction lately. However, the current scaffolds are based on a relatively limited set of design principles and ligand platforms associated therewith. We herein focus on the synthesis as well as versatile oxidation, addition and coordination chemistry of geometrically distorted P(III) species featuring a synthetically modular, nonsymmetric trisamine platform derived from 2‐(methylamino)‐N‐(2‐(methylamino)phenyl)benzenesulfonamide.

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“…1,3,2-Diazaphospholenes (DAPs) are heterocycles that contain a carbon–carbon double bond and two nitrogen atoms separated by a phosphorus atom. These compounds have been widely used as catalysts in organic synthesis, mainly due to the unique reactivity of P-hydrido substituted members of this family [ 121 ]. The most widely used protocol for their synthesis is a two-step process consisting of reduction of the 1,4-diaza-1,3-butadiene 272 with lithium or sodium to afford the corresponding dianion, which could react directly with PCl 3 or could be protonated first with triethylamine hydrochloride, and after that, react with PCl 3 to afford the respective P -chloro-1,3,2-diazaphospholene derivatives 273 .…”

Section: Synthesis Of Heterocycles Using 14-diaza-13-butadienesmentioning

confidence: 99%

Diaza-1,3-butadienes as Useful Intermediate in Heterocycles Synthesis

et al. 2022

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Many heterocyclic compounds can be synthetized using diaza-1,3-butadienes (DADs) as key structural precursors. Isolated and in situ diaza-1,3-butadienes, produced from their respective precursors (typically imines and hydrazones) under a variety of conditions, can both react with a wide range of substrates in many kinds of reactions. Most of these reactions discussed here include nucleophilic additions, Michael-type reactions, cycloadditions, Diels–Alder, inverse electron demand Diels–Alder, and aza-Diels–Alder reactions. This review focuses on the reports during the last 10 years employing 1,2-diaza-, 1,3-diaza-, 2,3-diaza-, and 1,4-diaza-1,3-butadienes as intermediates to synthesize heterocycles such as indole, pyrazole, 1,2,3-triazole, imidazoline, pyrimidinone, pyrazoline, -lactam, and imidazolidine, among others. Fused heterocycles, such as quinazoline, isoquinoline, and dihydroquinoxaline derivatives, are also included in the review.

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Stay positive: catalysis with 1,3,2-diazaphospholenes

Abstract: P–hydrido 1,3,2-diazaphospholenes (DAPs) are a class of nucleophilic molecular hydrides capable of addition to a variety of substrates. They can be turned over with terminal reductants and emerged over the...

Cited by 20 publications

References 47 publications

Chemoselective catalytic hydrodefluorination of trifluoromethylalkenes towards mono-/gem-di-fluoroalkenes under metal-free conditions

Chemoselective catalytic hydrodefluorination of trifluoromethylalkenes towards mono-/gem-di-fluoroalkenes under metal-free conditions

Geometrically Deformed and Conformationally Rigid Phosphorus Trisamides Featuring an Unsymmetrical Backbone

Diaza-1,3-butadienes as Useful Intermediate in Heterocycles Synthesis

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