Alkynylcarbenium ions and related unsaturated cations

Lukyanov, S. M.; Koblik, A. V.; Muradyan, L. A.

doi:10.1070/rc1998v067n10abeh000410

Cited by 13 publications

(4 citation statements)

References 196 publications

(255 reference statements)

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“…Propargyl cations1 have been known in organic chemistry for quite some time both as the reactive intermediates in Meyer−Schuster and Rupe rearrangements,2 as well as persistent species in solution3 and in the solid state 4. Due to their unsymmetrical constitution they are an interesting class of ambident electrophiles that furnish either propargyl derivatives or allenes upon nucleophilic trapping.…”

Section: Introductionmentioning

confidence: 99%

“…Both the electronic and structural features of propargyl cations have been extensively investigated in the past, leading to the conclusion that propargyl cations can be considered as alkynyl‐substituted carbenium ions with their ambident reactivity largely depending on the substitution pattern at the α‐ and the γ‐ positions 3b,3e. This classifies them as an intriguing class of reactive species that can open the way to highly unsaturated structures for the elaboration of syntheses of complex molecules 1…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stereoselective Propargylations with Transition-Metal-Stabilized Propargyl Cations

Müller

2001

Eur. J. Org. Chem.

117

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“…All these results seem to indicate that the reaction proceeds through the formation of a stabilized carbonium intermediate. [14] The reactions described above for the metal-free catalytic synthesis of heteroatom-substituted propargylic compounds undoubtedly represent a significant achievement as they provide a competitive method to the known strategies for the synthesis of these kinds of compounds. From the point of view of organic synthesis, however, a major challenge is the creation of new carbon-carbon bonds.…”

Section: Resultsmentioning

confidence: 99%

Metal‐Free Catalytic Nucleophilic Substitution of Propargylic Alcohols

et al. 2006

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Organic acids such as PTS efficiently catalyze direct nucleophilic substitutions of the hydroxy groups of propargylic alcohols with a large variety of carbon‐ and heteroatom‐centered nucleophiles. Reactions can be conducted under mild conditions and in air without the need for dried solvents. Reactions on multigram scales are also possible. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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“…To our satisfaction, the ether 3t (R = C 2 H 5 ) was selectively obtained in 92% yield (Scheme c). This can be explained by the formation of the alkynyl carbocation intermediate, from the elimination of a water molecule, followed by the nucleophilic attack by the alcohol solvent . The elimination of water from the propargyl alcohol is favored in the acidic medium of the reaction, due to the presence of Oxone (pH = 1).…”

Section: Resultsmentioning

confidence: 99%

Synthesis of 4-Selanyl- and 4-Tellanyl-1H-isochromen-1-ones Promoted by Diorganyl Dichalcogenides and Oxone

et al. 2021

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A new method was developed for the synthesis of 4-chalcogenyl-1H-isochromen-1-ones through the 6-endo-dig electrophilic cyclization of 2-alkynylaryl esters and diorganyl dichalcogenides under ultrasound irradiation. The reactions were performed under mild conditions, using Oxone as a green oxidant to promote the cleavage of the chalcogen–chalcogen bond in diorganyl diselenides and ditellurides to generate electrophilic species in situ. A total of 25 compounds were selectively obtained after 30–70 min, in good to excellent yields (74–95%). This procedure was extended to prepare 5H-selenopheno[3,2-c]isochromen-5-ones. Additionally, for the first time, the 4-chalcogenyl-1H-isochromen-1-ones were used as substrates in the thionation reaction, using Lawesson’s reagent and microwave irradiation under solvent-free conditions, obtaining the thio derivatives in yields of up to 99% in only 15 min.

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Alkynylcarbenium ions and related unsaturated cations

Cited by 13 publications

References 196 publications

Stereoselective Propargylations with Transition-Metal-Stabilized Propargyl Cations

Stereoselective Propargylations with Transition-Metal-Stabilized Propargyl Cations

Metal‐Free Catalytic Nucleophilic Substitution of Propargylic Alcohols

Synthesis of 4-Selanyl- and 4-Tellanyl-1H-isochromen-1-ones Promoted by Diorganyl Dichalcogenides and Oxone

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