Propellicene or Bi-2,13-pentahelicenylene.

Thulin, Bengt; Wennerström, Olof; Nielsen, Bent; Johnson, I.; Taticchi, A.; Anthonsen, T.

doi:10.3891/acta.chem.scand.30b-0688

Cited by 43 publications

(19 citation statements)

References 0 publications

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“…Molecules with a figure‐eight conformation are known in other fields. Such geometry has been determined for propellicenes31 and [28]paracyclophaneoctaene 32. This motif has been also observed among cyclic peptides33 and coordination compounds 34…”

Section: Resultsmentioning

confidence: 56%

Figure-Eight Tetrathiaoctaphyrin and Dihydrotetrathiaoctaphyrin

Sprutta

Latos‐Grażyński

2001

Chem. Eur. J.

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The acid-catalyzed condensation of pyrrole and 2,5-bis(p-tolylhydroxymethyl)thiophene yields two novel giant heteroporphyrins: 5,10,15,20,25,30, 35,40-octa(p-tolyl)-41,43,45,47-tetrathia[36]octaphyrin(1.1.1.1.1.1.1.1) (S4OP) and 5,10,15,20,25,30,35,40-octa(p-tolyl)-dihydro-41,43,45,47-tetrathia[38]octaphyrin(1.1.1.1.1.1.1.1) (S4OPH2). These tetrathiaoctaphyrins are interconvertible through dihydrogenation or dehydrogenation processes. Both compounds possess helical figure-eight geometry with two thiophene rings for S4OP or two pyrrole rings for S4OPH2 in the ribbon-crossing center as shown by NOESY experiments. The synthesis of the figure-eight tetrathiaoctaphyrin implies a prearrangement process to form helical M or P dithiatetrapyrromethanes. The P-P or M-M condensation leads to the figure-eight molecule in competition with an intramolecular ring closure. Two dithiaporphyrin-like pockets of S4OP or S4OPH2 behave as independent proton acceptors. The stepwise process yields symmetric or asymmetric cationic species that depends on whether an even or odd number of NH protons are added. Dihydrotetrathiaoctaphyrin contains 38 pi electrons in its conjugation pathway, which corresponds to the formal [4n + 2] Hückel type pi-electron formulation that is consistent with a modest diatropic ring current effect in their 1H NMR spectra. The formal 4n type pi-electron formulation for tetrathiaoctaphyrin accounts for the residual paratropic shifts. A figure-eight conveyor-belt-like movement of the whole macrocyclic ring without a racemization step is proposed to account for the dynamic properties of S4OP. The molecule shuttles between two degenerate configurations. A S4OP-S4OPH2 couple may be considered as a molecular element which, while preserving the overall figure-eight geometry, "chooses" pyrrole or thiophene rings as spacers as a function of the macrocyclic oxidation state.

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Section: Resultsmentioning

confidence: 56%

Figure-Eight Tetrathiaoctaphyrin and Dihydrotetrathiaoctaphyrin

Sprutta

Latos‐Grażyński

2001

Chem. Eur. J.

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“…For example, Wennerström and coworkers have reported the synthesis of a series of helical cyclophanes based on cis-alkenes as building blocks and using Wittig chemistry to effect cyclization [26]. These cyclophanes (61)(62)(63)(64) possess varying degrees of conformational flexibility dependent upon the tether employed.…”

Section: Helical Chirality Using Achiral Building Blocksmentioning

confidence: 99%

“…Recently, there has been an increasing number of reports of macrocycles that are chiral due to the incorporation of a helicene moiety [62]. One of the earliest structures to be reported was from Wennerström and coworkers [63] and linked directly two [5]helicenes to give macrocycle 169, which came to be known as propellicene.…”

Section: Chiral Macrocycles Using Chiral Carbon-rich Building Blocksmentioning

confidence: 99%

Chiral Carbon‐rich Macrocycles and Cyclophanes

Campbell

Tykwinski

2006

Carbon‐Rich Compounds

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“…At present, most studies focus aromatic compounds with one or three half-twist of the p surface, [26][27][28][29][30][31][32][33][34] and planar p-conjugated aromatic compounds with two half-twist of the p surface. 27,28,35,36 However, very little research has been done on radial p-conjugated aromatic compounds with two half-twist of the p surface, which adopts gure eight (lemniscular) shape and helps maximize p orbital overlap and reduce internal strain.…”

Section: Introductionmentioning

confidence: 99%