Reaction of Dicobalthexacarbonyl Propargyl Cations with Aldehydic<i>N,N</i>-Dibenzylenamines

Roth, Kurt

doi:10.1055/s-1992-21372

Cited by 25 publications

(13 citation statements)

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“…For 2e (Fig- [g] Data for the process Fl!FlC À ;m easured by CV as E 1/2 (Fl/FlC À )u sing Fc + /Fc 0 standard and then recalculated relative to SCE. [27] [h] Data for the process FlC + + !Fl;measured by CV as oxidative E p using Fc + /Fc 0 standarda nd then recalculated relative to SCE. [27] [i]Estimatede xciteds tate redox potentialf or Fl!FlC vs. SCE;c alculated by E red (S 1 ) = E red + E 0,0 (S 1 )o rE red (T 1 ) = E red + E 0,0 (T 1 ).…”

Section: Electrochemical and Photophysical Propertiesmentioning

confidence: 99%

Flavin Photocatalysts for Visible‐Light [2+2] Cycloadditions: Structure, Reactivity and Reaction Mechanism

et al. 2018

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New photocatalysts from the flavin family were found to mediate the [2+2] photocycloaddition reaction. 3‐Butyl‐10‐methyl‐5‐deazaflavin (3 a) and 1‐butyl‐7,8‐dimethoxy‐3‐methylalloxazine (2 e), if irradiated by visible light, were shown to allow an efficient (Φ≈3–10 %) intramolecular cyclisation of various types of substrates including substituted styrene dienes and bis(aryl enones), considered as electron‐rich and electron‐poor substrates, respectively, without any additional reagent. The versatility of the procedure was demonstrated by the cyclisation of photosensitive cinnamyl (E)‐3‐iodoallyl ether. Structure–activity studies found alloxazine 2 e was more active than 7‐monosubstituted (R=Cl, Br and MeO) alloxazines. The introduction of chlorine and bromine atom on the deazaflavin skeleton did not enhance the catalytic efficiency of 3 a. A detailed electrochemical and spectroscopic study explains the reaction mechanism proceeding through energy transfer from the flavin excited triplet state to the diene followed by its cyclisation.

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Section: Electrochemical and Photophysical Propertiesmentioning

confidence: 99%

Flavin Photocatalysts for Visible‐Light [2+2] Cycloadditions: Structure, Reactivity and Reaction Mechanism

et al. 2018

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“…Roth showed that the nucleophilic addition of the aldehyde N , N ‐dibenzyl enamines 12 to Nicholas’ cations 3 furnishes organometallic derivatives of iminium salts 13 which were subsequently reacted in the same pot with Grignard reagents or trimethylsilyl cyanide (Scheme ) to give the highly substituted complexes 14 and, after decomplexation, the corresponding propargyl derivatives 15 22. This consecutive nucleophilic trapping of Nicholas’ cation 3 and the iminium salt 13 is a highly interesting cascade reaction since it not only takes advantage of nucleophiles with specific reactivity, with simultaneous formation of two new carbon−carbon bonds, but it also establishes three contiguous stereogenic centers in a one pot process with decent to good diastereoselectivity.…”

Section: Propargyl Cation Complexes (With Complexation Of the Tripmentioning

confidence: 99%

Stereoselective Propargylations with Transition-Metal-Stabilized Propargyl Cations

Müller

2001

Eur. J. Org. Chem.

117

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Cationic propargylations have been known for quite some time but only the advent of transition metal stabilization has initiated their stereoselective applications. The introduction of nucleophilic additions to dicobalthexacarbonyl‐complexed propargyl cations, known as the Nicholas reaction, has led to widespread applications in the synthesis of complex molecules. Besides the stabilization by direct complexation of the triple bond, the complementary mode, i.e. transition metal complex substituents as propargyl cation stabilizing functional groups, is almost unknown. However, upon ionization, ferrocenyl‐ and (arene)chromiumcarbonyl‐substituted propargyl derivatives give the desired cationic species, and these cations can be regarded as quite reactive propargyl cations without simultaneous complexation of the triple bond, thus enabling highly diastereoselective nucleophilic additions with the potential of exploiting the ambident nature of propargyl cations.

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“…In designing as trategy to construct CÀNb onds by photoredox catalysis using aliphatic amines (Scheme 1b), it is noteworthy that both aliphatic amines and electron-rich arenes can be oxidized by the acridinium photocatalyst to the corresponding cation radicals (see Table S1 in the Supporting Information). [21] To examine whether aryl amination could occur using aliphatic amines,irradiation (455 nm LEDs) of an arene and an amino ester hydrochloride salt in the presence of the acridinium photocatalyst Me 2 -Mes-Acr + in am ixture of 1,2-dichloroethane (DCE) and pH 8p hosphate buffer afforded the aminated arene products ( Figure 1). Aw ide variety of amino ester hydrochloride salts participated in the reaction, providing access to N-arylated amino acids under mild reaction conditions.Whenanisole was used as the arene coupling partner,the ortho isomer was favored in all cases,in moderate to excellent yields (1a-14 a), complimentary to the aryl amination previously reported by our laboratory.T he regioselectivity could be reversed by employing tert-butyldimethylsilyl (TBS) phenyl ether as the arene,f avoring the formation of the para isomer (1b-14 b).…”

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confidence: 99%

Direct Aryl C−H Amination with Primary Amines Using Organic Photoredox Catalysis

2017

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The direct catalytic C–H amination of arenes is a powerful synthetic strategy with useful applications in pharmaceuticals, agrochemicals, and materials chemistry. Despite the advances in catalytic C–H functionalization, the use of aliphatic amine coupling partners is limited. Described herein is the construction of C–N bonds, using primary amines, by direct C–H functionalization with an acridinium photoredox catalyst under an aerobic atmosphere. A wide variety of primary amines, including amino acids and more complex amines are competent coupling partners. Various electron-rich aromatics and heteroaromatics are useful scaffolds in this reaction, as are complex, biologically active arenes. We also describe the ability to functionalize arenes that are not oxidized by an acridinium catalyst, such as benzene and toluene, thus supporting a reactive amine cation radical intermediate.

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Reaction of Dicobalthexacarbonyl Propargyl Cations with AldehydicN,N-Dibenzylenamines

Cited by 25 publications

References 0 publications

Flavin Photocatalysts for Visible‐Light [2+2] Cycloadditions: Structure, Reactivity and Reaction Mechanism

Flavin Photocatalysts for Visible‐Light [2+2] Cycloadditions: Structure, Reactivity and Reaction Mechanism

Stereoselective Propargylations with Transition-Metal-Stabilized Propargyl Cations

Direct Aryl C−H Amination with Primary Amines Using Organic Photoredox Catalysis

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