Synthesis of 3,3-dimethyl-1-phenyl-2-phenylethynylcyclopropene - the first conjugated alkynylcyclopropene

Кузнецов, М. А.; Dorofeeva, Yu. V.; Semenovskii, V. V.; Gindin, V. A.; Studenikov, A. N.

doi:10.1016/s0040-4020(01)90789-6

Cited by 16 publications

(3 citation statements)

References 15 publications

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“…The set of characteristic frequencies found for this species and its d 2 -counterpart (Supporting Information) corresponds to the structure of 1-ethynyl-3,3-dimethylcyclopropene ( 4 ). These frequencies correlate well with the corresponding fundamental frequencies of the series of cyclopropenes ,,− , obtained in low-temperature matrices and with the respective frequencies of the first stable 1-ethynylcyclopropene, 3,3-dimethyl-1-phenyl-2-phenylethynylcyclopropene . It is worth noting that no ethynylcyclopropene has been observed by matrix spectroscopy before.…”

Section: Resultssupporting

confidence: 80%

“…These frequencies correlate well with the corresponding fundamental frequencies of the series of cyclopropenes 34,55,[62][63][64][65]79 obtained in low-temperature matrices and with the respective frequencies of the first stable 1-ethynylcyclopropene, 3,3-dimethyl-1-phenyl-2-phenylethynylcyclopropene. 80 It is worth noting that no ethynylcyclopropene has been observed by matrix spectroscopy before. The PBE/TZ2P calculated IR spectra of 4 and d 2 -4 are in a good agreement with those observed in the experiments (Supporting Information).…”

Section: Phototransformations Of 5-methylhexa-124-triene-13-diylmentioning

confidence: 99%

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A Highly Delocalized Triplet Carbene, 5-Methylhexa-1,2,4-triene-1,3-diyl: Matrix IR Identification, Structure, and Reactions

et al. 2009

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The first representative of highly delocalized triplet carbenes bearing both vinyl and ethynyl groups at the formal carbene center, 5-methylhexa-1,2,4-triene-1,3-diyl, has been generated in a low-temperature Ar matrix upon UV photolysis of 5-ethynyl-3,3-dimethyl-3H-pyrazole and detected by FTIR spectroscopy. The transformation of 3H-pyrazole into the carbene proceeds in two stages via intermediate 3-diazo-5-methylhex-4-en-1-yne. According to DFT PBE/TZ2P calculations, 5-methylhexa-1,2,4-triene-1,3-diyl possesses an effective conjugation along the five-carbon chain and shows the same type of the bond length alternation as the HC(4m+1)H-type polyacetylenic carbenes. The carbene readily reacts with molecular oxygen, producing carbonyl oxides, which undergo further transformations typical of this type of compound upon irradiation in the UV-visible region. Two major photolytic rearrangements of 5-methylhexa-1,2,4-triene-1,3-diyl represent reactions characteristic of vinyl carbenes and resulting in the formation of 1-ethynyl-3,3-dimethylcyclopropene and 3E-2-methylhexa-1,3-dien-5-yne. A minor reaction is that typical of ethynylcarbenes; this leads to the formation of singlet 2-(2-methylpropenyl)cyclopropenylidene. Fragments of singlet and triplet potential energy surfaces of the C(7)H(8) system have been explored in DFT PBE/TZ2P calculations.

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Section: Resultssupporting

confidence: 80%

Section: Phototransformations Of 5-methylhexa-124-triene-13-diylmentioning

confidence: 99%

A Highly Delocalized Triplet Carbene, 5-Methylhexa-1,2,4-triene-1,3-diyl: Matrix IR Identification, Structure, and Reactions

et al. 2009

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“…However, terminal cyclopropenes with two electron-withdrawing groups are required for efficient C-H activation, resulting in a narrow scope. Monocyclopropenation of 1,3-diynes by transition-metal-catalysed reaction of diazo compounds or their surrogates is also a viable process affording alkynyl cyclopropenes [43][44][45][46] , but is limited to symmetrical 1,3-diynes. Therefore, the coupling of CpBX 1a bearing one ester group on the C3 position and phenylacetylene (2a) was selected as our prototypical system.…”

Section: Reaction Developmentmentioning

confidence: 99%

Accessing elusive σ-type cyclopropenium cation equivalents through redox gold catalysis

Li,

Wodrich,

Waser

2024

Nat. Chem.

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Cyclopropenes are the smallest unsaturated carbocycles. Removing one substituent from cyclopropenes leads to cyclopropenium cations (C3+ systems, CPCs). Stable aromatic π-type CPCs were discovered by Breslow in 1957 by removing a substituent on the aliphatic position. In contrast, σ-type CPCs—formally accessed by removing one substituent on the alkene—are unstable and relatively unexplored. Here we introduce electrophilic cyclopropenyl-gold(III) species as equivalents of σ-type CPCs, which can then react with terminal alkynes and vinylboronic acids. With catalyst loadings as low as 2 mol%, the synthesis of highly functionalized alkynyl- or alkenyl-cyclopropenes proceeded under mild conditions. A class of hypervalent iodine reagents—the cyclopropenyl benziodoxoles (CpBXs)—enabled the direct oxidation of gold(I) to gold(III) with concomitant transfer of a cyclopropenyl group. This protocol was general, tolerant to numerous functional groups and could be used for the late-stage modification of complex natural products, bioactive molecules and pharmaceuticals.

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Acetone Hydrazone

Peralta¹

2001

Encyclopedia of Reagents for Organic Synthesis

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Synthesis of 3,3-dimethyl-1-phenyl-2-phenylethynylcyclopropene - the first conjugated alkynylcyclopropene

Cited by 16 publications

References 15 publications

A Highly Delocalized Triplet Carbene, 5-Methylhexa-1,2,4-triene-1,3-diyl: Matrix IR Identification, Structure, and Reactions

A Highly Delocalized Triplet Carbene, 5-Methylhexa-1,2,4-triene-1,3-diyl: Matrix IR Identification, Structure, and Reactions

Accessing elusive σ-type cyclopropenium cation equivalents through redox gold catalysis

Acetone Hydrazone

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