9,9',10,10'-Tetradehydrodianthracene. Formation, protection, and regeneration of a strained double bond

Viavattene, Ronald L.; Greene, Frederick D.; CHEUNG, L. D.; Majeste, R. J.; Trefonas, L. M.

doi:10.1021/ja00820a058

Cited by 94 publications

(46 citation statements)

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“…In 1974, Greene and co-workers reported the synthesis of TDDA 4 (Scheme 1) [9] by the [4+ +4] photocyclization of 9-bromoantharacene (1), which afforded dimer 2.Asubsequent dehydrobromination of 2 with KO t Bu/LiTMP/KN(SiMe 3 ) 2 , followed by reaction with sodium azide led to precursor 3. Tr eatment of 3 with KO t Bu and Carpinos reagent (mesityl-SO 3 NH 2 ,m esityl = 2,4,6-trimethylphenyl) afforded 4,w hich represents a( 2,2)CNT segment.…”

Section: Katsuma Matsui Was Born Inmentioning

confidence: 99%

“…As ar esult, [9]CPP and [12]CPP were synthesized in merely four steps from commercially available starting materials.T his concise method can also be easily scaled up and, accordingly,l arge amounts Angewandte Chemie Reviews (ca. 10 g) of [9]CPP and [12]CPP are now commercially available. [31] TheI tami group furthermore established as ize-selective synthesis for [7]- [16]CPPs (Scheme 16) through ac ombination of L-shaped building blocks 59 b,c and 76 a with linear units.Initially,the size-selective synthesis of large CPPs, [14]- [16]CPPs,w as accomplished by assembling an L-shaped unit 59 b with 1,4-diborylbenzene and 4,4'-diborylbiphenyl to yield U-shaped units 64 a and 65 a,r espectively.…”

Section: Angewandte Chemiementioning

confidence: 99%

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Design and Synthesis of Carbon Nanotube Segments

et al. 2016

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Section: Katsuma Matsui Was Born Inmentioning

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Section: Angewandte Chemiementioning

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Design and Synthesis of Carbon Nanotube Segments

et al. 2016

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“…Our structure search in the Cambridge Structural Database (CSD) revealed a subunit in the structure of 9,9′,10,10′-tetradehydrodianthracene that resembles the (Z,E,Z,E)-COT structure (22). The CSD also contains one fascinating molecule, a di-Fe(CO) 3 complex of COT that approximates this geometry (23), but the organometallic bonding naturally changes the bonding picture.…”

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Stabilizing a different cyclooctatetraene stereoisomer

Lei

Xie

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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An unconventional cis-cis-cis-trans or (Z,Z,Z,E) structure B of cyclooctatetraene (COT) is calculated to lie only 23 kcal/mol above the well-known tub-shaped (Z,Z,Z,Z) isomer A; one example of this type of structure is known. The barrier for B returning to A is small, 3 kcal/mol. However, by suitable choice of substituents, the (Z,Z,Z,E) isomer can be made to lie in energy below the tub-shaped structure. Steric, clamping, and electronic strategies are proposed for achieving this. In the steric strategy, the C 8 H 4 (CH 3 ) 2 (C( t Bu) 3 ) 2 structure B is predicted to lie 21 kcal/mol below structure A, which is separated from form B only by a small barrier. A simple clamping strategy, effective for COT planarization, does not influence the A/B isomerization much. But, if the clamping group is aromatic (a fused benzene, pyrrole, thiophene, furan), the subtle interplay of potential aromaticity with clamping can be used to confer persistence if not stability on the (Z,Z,Z,E) isomer. An electronic strategy of a different kind, push-pull substitution on the COT ring, was not very effective in stabilizing the B form. However, it led us to vicinal amine-borane-substituted normal COTs that proved to be quite good at activating H 2 in a frustrated Lewis pair scenario. The molecule is most certainly not aromatic, in accord with Hückel's rule (2). It features four cis-or Z double bonds in a characteristic nonplanar D 2d tub shape (3). From a combined femtosecond rotational coherence spectroscopy and theoretical study we have the molecule's precise gas-phase structure, with bond lengths r e (C-C) = 1.470, r e (C=C) = 1.337, and r e (C-H) = 1.079 Å (4). Potential ring inversion and bond-bond switching in COT have fascinated the organic community for decades (5-7). The planar D 4h structure of COT is a transition state (TS) for the ring inversion (calculated barrier height of 10-14 kcal/mol) (8-12). The D 8h bondswitching TS lies a few kilocalories per mole higher. The accepted automerization surface is summarized schematically in Fig. 1.Motivated by the recent determination of the structures of some asymmetrically substituted COTs (13), we began a systematic study of COTs. Some peculiar geometries, far away from the tub shape, emerged; in time we identified them as cis-cis-cistrans (Z,Z,Z,E) isomers of COT. Stabilizing these structures is the aim of this article.(Z,Z,Z,E)-COT structures already appear in the theoretical and experimental literature. Conesa and Rzepa in 1998 predicted this isomer to lie 21-29 kcal/mol above the conventional all-Z structure, with a small barrier to return to all-Z COT (14). In their studies of Möbius aromaticity, Havenith et al. (15) optimized a C 8 H 8 (Z,Z,Z,E) structure, finding it again 21-29 kcal/mol above (Z,Z,Z,Z). And, in a comprehensive paper on the photochemistry and thermal rearrangements of COT, Garavelli et al. (16) found the (Z,Z,Z,E) isomer as a reaction intermediate, 24 to 25 kcal/mol above normal COT. The primary interest in their wideranging paper was in the photochemistry o...

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“…Tetradehydrodiepoxydianthracene 7: A solution of 191.1 mg (1.136 mmol) of m-chloroperbenzoic acid in 100 ml of dichloromethane was added dropwise to a solution of 200 mg (0.568 mmol) of tetradehydrodianthracene [21] in 200 ml of dichloromethane. The mixture was stirred for 30 min at room temp.…”

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