An isolable o-quinodimethane and its fixation of molecular oxygen to give an endoperoxide

Ghereg, Dumitru; Kettani, Sakina Ech-Cherif El; Lazraq, M.; Ranaivonjatovo, H.; Schoeller, Wolfgang W.; Escudié, J.; Gornitzka, Heinz

doi:10.1039/b910001f

“…These compounds were generated and detected in rigid glass matrices but could not be isolated. Though tetraaryl‐ o QDM 11 18 and a highly reactive o QDM derivative 12 19 were recently synthesized and isolated, the fundamental properties originating from the o QDM moiety remain to be clarified. In this regard, indeno[2,1‐ a ]fluorene ( 6 a ) is an intriguing molecule because the benzo bridge to the o QDM structure would not only extend the length of the π‐conjugated carbon framework but also prevent one of the typical reactions of o QDMs, cyclization to form benzocyclobutenes.…”

Section: Methodsmentioning

confidence: 99%

“…However, more detailed examination of the bond lengths leads to some modification of the geometrical structures. Bond a in 6 c is longer than a regular C(sp 2 )–C(sp 2 ) double bond (1.349 Å),28 the corresponding bond of o QDM calculated at the RB3LYP/6‐31G(d) level of theory, and those of the previously isolated o QDMs ( 11 : 1.346(6)18 and 12 : 1.356(11) Å,19 mean values). The bond‐length elongation reminds us of the discussion in connection with Thiele’s and Chichibabin’s hydrocarbons 15.…”

Section: Methodsmentioning

confidence: 99%

Indeno[2,1‐a]fluorene: An Air‐Stable ortho‐Quinodimethane Derivative

Shimizu

¹

,

Tobe

²

2011

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Conjugated polycyclic hydrocarbons [1] have attracted much attention because of their novel fundamental properties and potential application in electronic materials. [2] Recently, thanks to the development of excellent synthetic methods, hydrocarbons with unique electronic structures such as dibenzopentalenes 1[3] and zethrenes 2 [4] have been subjects of extensive research. In particular, polycyclic hydrocarbons containing a quinodimethane (QDM) structure [5, 6] have been studied because of their low-energy bandgaps and excellent electrochemical behavior, which make them potential candidates for optoelectronic materials.Very recently, Haley et al. have reported the synthesis and properties of a stable p-quinodimethane (pQDM) derivative, indeno [1,2-b]fluorene 3 b (TIPS = triisopropylsilyl) [5] which was regarded as a fully conjugated 20p-electron hydrocarbon with fused s-trans diene linkages across the top and bottom parts of the carbon framework. [7,8] In connection with our own interest in the transannular cyclization of dehydrobenzoannulenes, [9] we became interested in a structural isomer of 3 a, indeno[2,1-a]fluorene (6 a), which possesses an o-quinodimethane (oQDM) structure instead of the pQDM moiety of 3 a, for two reasons: 1) Since oQDM [10] has a smaller HOMO-LUMO energy gap than pQDM, [11] the HOMO-LUMO gap of 6 a would be smaller than that of 3 a. 2) In contrast to the pQDM derivatives, studies on compounds containing an oQDM structure are scarce because of their high reactivity due to the s-cis diene unit. [12] In fact, studies on pQDM-type hydrocarbons such as Thieles hydrocarbon 7[13] and Chichibabins hydrocarbon 8, [14] which are stable enough to be isolated as crystals, [15] were performed over a century ago. On the other hand, molecules containing the oQDM structure, such as tetraphenyl-oQDM 9 [16] and pleiadene (10) [17] are reported to be highly reactive. These compounds were generated and detected in rigid glass matrices but could not be isolated. Though tetraaryl-oQDM 11 [18] and a highly reactive oQDM derivative 12 [19] were recently synthesized and isolated, the fundamental properties originating from the oQDM moiety remain to be clarified. In this regard, indeno-[2,1-a]fluorene (6 a) is an intriguing molecule because the benzo bridge to the oQDM structure would not only extend the length of the p-conjugated carbon framework but also prevent one of the typical reactions of oQDMs, cyclization to form benzocyclobutenes. Additionally, the fact that 6 a contains an antiaromatic as-indacene moiety, which has not been isolated to date, [20] also makes 6 a a fascinating hydrocarbon.Le Berre et al. synthesized the 11,12-diphenyl derivative 6 b [21] which exhibited an absorption maximum at 556 nm. However, 6 b turned out to be highly reactive toward oxygen [22] and therefore its molecular structure and detailed electronic structures, such as electrochemical behavior and ring-current effect, have not been investigated. In addition, a series of reports by Le Berre et al. in the mid-1950s are the

show abstract

“…[ lated at the RB3LYP/6-31G(d) level of theory, and those of the previously isolated oQDMs (11: 1.346(6) [18] and 12: 1.356(11) , [19] mean values). The bond-length elongation reminds us of the discussion in connection with Thieles and Chichibabins hydrocarbons.…”

mentioning

confidence: 99%

“…These compounds were generated and detected in rigid glass matrices but could not be isolated. Though tetraaryl-oQDM 11 [18] and a highly reactive oQDM derivative 12 [19] were recently synthesized and isolated, the fundamental properties originating from the oQDM moiety remain to be clarified. In this regard, indeno-[2,1-a]fluorene (6 a) is an intriguing molecule because the benzo bridge to the oQDM structure would not only extend the length of the p-conjugated carbon framework but also prevent one of the typical reactions of oQDMs, cyclization to form benzocyclobutenes.…”

mentioning

confidence: 99%

Indeno[2,1‐a]fluorene: An Air‐Stable ortho‐Quinodimethane Derivative

Shimizu

¹

,

Tobe

²

2011

View full text Add to dashboard Cite

Conjugated polycyclic hydrocarbons [1] have attracted much attention because of their novel fundamental properties and potential application in electronic materials. [2] Recently, thanks to the development of excellent synthetic methods, hydrocarbons with unique electronic structures such as dibenzopentalenes 1[3] and zethrenes 2 [4] have been subjects of extensive research. In particular, polycyclic hydrocarbons containing a quinodimethane (QDM) structure [5, 6] have been studied because of their low-energy bandgaps and excellent electrochemical behavior, which make them potential candidates for optoelectronic materials.Very recently, Haley et al. have reported the synthesis and properties of a stable p-quinodimethane (pQDM) derivative, indeno [1,2-b]fluorene 3 b (TIPS = triisopropylsilyl) [5] which was regarded as a fully conjugated 20p-electron hydrocarbon with fused s-trans diene linkages across the top and bottom parts of the carbon framework. [7,8] In connection with our own interest in the transannular cyclization of dehydrobenzoannulenes, [9] we became interested in a structural isomer of 3 a, indeno[2,1-a]fluorene (6 a), which possesses an o-quinodimethane (oQDM) structure instead of the pQDM moiety of 3 a, for two reasons: 1) Since oQDM [10] has a smaller HOMO-LUMO energy gap than pQDM, [11] the HOMO-LUMO gap of 6 a would be smaller than that of 3 a. 2) In contrast to the pQDM derivatives, studies on compounds containing an oQDM structure are scarce because of their high reactivity due to the s-cis diene unit. [12] In fact, studies on pQDM-type hydrocarbons such as Thieles hydrocarbon 7[13] and Chichibabins hydrocarbon 8, [14] which are stable enough to be isolated as crystals, [15] were performed over a century ago. On the other hand, molecules containing the oQDM structure, such as tetraphenyl-oQDM 9 [16] and pleiadene (10) [17] are reported to be highly reactive. These compounds were generated and detected in rigid glass matrices but could not be isolated. Though tetraaryl-oQDM 11 [18] and a highly reactive oQDM derivative 12 [19] were recently synthesized and isolated, the fundamental properties originating from the oQDM moiety remain to be clarified. In this regard, indeno-[2,1-a]fluorene (6 a) is an intriguing molecule because the benzo bridge to the oQDM structure would not only extend the length of the p-conjugated carbon framework but also prevent one of the typical reactions of oQDMs, cyclization to form benzocyclobutenes. Additionally, the fact that 6 a contains an antiaromatic as-indacene moiety, which has not been isolated to date, [20] also makes 6 a a fascinating hydrocarbon.Le Berre et al. synthesized the 11,12-diphenyl derivative 6 b [21] which exhibited an absorption maximum at 556 nm. However, 6 b turned out to be highly reactive toward oxygen [22] and therefore its molecular structure and detailed electronic structures, such as electrochemical behavior and ring-current effect, have not been investigated. In addition, a series of reports by Le Berre et al. in the mid-1950s are the

show abstract

“…Nevertheless, the p system of pyrene and the two o-quinoid C=C double bonds of 8 b can be considered to be still fully conjugated. [23] In both conformers of 8 b, the C=C double-bond lengths C14=C21 and C5=C16 differ slightly (1.354 and 1.348 , respectively). The bond between the two exo double bonds (C16=C21) is 1.474 , that is, about 0.1 longer than in the bridged ketones 13 b and 13 c (C17=C18, 1.372 ; the related bond length in pyrene is 1.338 [24] ).…”

Section: Introductionmentioning

confidence: 96%

Pyrene‐Based Fluorescent Nitric Oxide Cheletropic Traps (FNOCTs) for the Detection of Nitric Oxide in Cell Cultures and Tissues

Düppe

¹

,

Talbierski

²

,

Hornig

³

et al. 2010

Chemistry A European J

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The synthesis and the structural and spectroscopic characterization of nonfluorescent, pyrene-based cyclic o-quinodimethanes are reported. These compounds react efficiently with nitric oxide (NO) in a formal cheletropic manner, by which the fluorescent aromatic pyrene system is regenerated. The NO trapping capabilities and kinetics of the fluorescent nitric oxide cheletropic traps (FNOCTs) are assessed in THF and buffered aqueous solution by ESR, UV/Vis, and fluorescence spectroscopy, by employing NO solutions and NO released from N-diazeniumdiolates (NONOates). Prototypal biological applications include the quantitation of NO production from cultured rat alveolar macrophages and the endothelium of porcine aorta, which demonstrate a sensitivity for NO detection in the nanomolar range.

show abstract

An isolable o-quinodimethane and its fixation of molecular oxygen to give an endoperoxide

Abstract: Addition of the germene Mes2Ge=CR2 to 1,4-naphthoquinone yields a singular o-quinodimethane which gives Diels-Alder reactions at room temperature and reacts cleanly with oxygen to form an endoperoxide.

Cited by 27 publications

References 31 publications

Indeno[2,1‐a]fluorene: An Air‐Stable ortho‐Quinodimethane Derivative

Indeno[2,1‐a]fluorene: An Air‐Stable ortho‐Quinodimethane Derivative

Indeno[2,1‐a]fluorene: An Air‐Stable ortho‐Quinodimethane Derivative

Pyrene‐Based Fluorescent Nitric Oxide Cheletropic Traps (FNOCTs) for the Detection of Nitric Oxide in Cell Cultures and Tissues

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