Reductive N Alkylation of Cyclo[8]pyrroles

Köhler, Thorsten; Ou, Zhongping; Lee, Jeong Tae; Seidel, Daniel; Lynch, Vincent M.; Kadish, Karl M.; Sessler, Jonathan L.

doi:10.1002/ange.200461801

Cited by 8 publications

(4 citation statements)

References 12 publications

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“…[39] Remarkably, when [72a- 4 ] is subjected to a reductive alkylation reaction it yields products of the general structure 73a-R 8 (R = Me, Et, Bn), which show no significant absorption above 325 nm. [254] 73a-R 8 is formally a [32]annulenoid system but it largely behaves as a cyclic oligopyrrole with insignificant macrocyclic conjugation. In the solid state, 73a-Me 8 adopts an alternant "four up, four down" conformation with the N-alkyl groups located on both sides of the macrocycle ( Figure 14).…”

Section: T0 Systemsmentioning

confidence: 99%

Figure Eights, Möbius Bands, and More: Conformation and Aromaticity of Porphyrinoids

2011

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The aromatic character of porphyrins, which has significant chemical and biological consequences, can be substantially altered by judicious modifications of the parent ring system. Expansion of the macrocycle, which is achieved by introducing additional subunits, usually increases the so-called free curvature of the ring, leading to larger angular strain. This strain is reduced by a variety of conformational changes, most notably by subunit inversion and p surface twisting. The latter effect creates a particularly convenient access to Möbius aromatic molecules, whose properties, predicted over 40 years ago, are of considerable theoretical importance. The conformational processes occurring in porphyrin analogues are often coupled to other chemical phenomena, and can thus be exploited as a means of constructing functional molecular devices. In this Review, the structural chemistry of porphyrinoids is discussed in the context of their conformational dynamics and p-electron conjugation.

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Section: T0 Systemsmentioning

confidence: 99%

Figure Eights, Möbius Bands, and More: Conformation and Aromaticity of Porphyrinoids

2011

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“…1100 nm ( ε ≈130 000 mol −1 cm −1 ) 39. Remarkably, when [ 72a ‐H 8 ][SO 4 ] is subjected to a reductive alkylation reaction it yields products of the general structure 73a ‐R 8 (R=Me, Et, Bn), which show no significant absorption above 325 nm 254 . 73a ‐R 8 is formally a [32]annulenoid system but it largely behaves as a cyclic oligopyrrole with insignificant macrocyclic conjugation.…”

Section: Octaphyrinsmentioning

confidence: 99%

Low-cost laparoscopic cholecystectomy (Br J Surg 2002; 89: 1602–1607)

Udwadia

2003

British Journal of Surgery

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The aromatic character of porphyrins, which has significant chemical and biological consequences, can be substantially altered by judicious modifications of the parent ring system. Expansion of the macrocycle, which is achieved by introducing additional subunits, usually increases the so‐called free curvature of the ring, leading to larger angular strain. This strain is reduced by a variety of conformational changes, most notably by subunit inversion and π surface twisting. The latter effect creates a particularly convenient access to Möbius aromatic molecules, whose properties, predicted over 40 years ago, are of considerable theoretical importance. The conformational processes occurring in porphyrin analogues are often coupled to other chemical phenomena, and can thus be exploited as a means of constructing functional molecular devices. In this Review, the structural chemistry of porphyrinoids is discussed in the context of their conformational dynamics and π‐electron conjugation

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“…It was thus clear that in order to account for global effects, as well as to access different oxidation states, the imide group must be replaced by groups such as alkyl, which cannot participate in the resonance of the π‐conjugated backbone. However, since the high HOMO level of furan intermediates renders them unstable throughout the synthetic procedure, we found that a previous strategy applied to macrocyclic thiophenes and pyrroles, namely, the macrocyclization of β‐alkyl‐monomers, [35] is not applicable for furan analogs. We therefore postulated that the reduction of the imide group (which stabilize the intermediates) to amine should be performed post‐macrocyclization [36,37] …”

Section: Introductionmentioning

confidence: 97%

A Macrocyclic Furan with Accessible Oxidation States: Switching Between Aromatic and Antiaromatic Global Ring Currents

Dishi

Rahav

Carmieli

et al. 2022

Chemistry A European J

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Macrocyclic furans are predicted to switch between global aromaticity and antiaromaticity, depending on their oxidation states. However, the macrocyclic furans reported to date are stabilized by electron withdrawing groups, which result in inaccessible oxidation states. To circumvent this problem, a post-macrocyclization approach was applied to introduce methylene-substituted macrocyclic furans, which display an extremely low oxidation potential of À 0.23 vs. Fc/ Fc + , and are partially oxidized in ambient conditions. Addi-tional oxidation to the dication results in aromaticity switching to a global 30πe À aromatic state, as indicated by the formation of a strong diatropic current observed in the 1 H NMR spectrum. NICS and ACID calculations support this trend and provide evidence for a different pathway for the global current in the neutral and dicationic states. According to these findings, macrocyclic furans can be rendered as promising p-type materials with stable oxidation states.

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Reductive N Alkylation of Cyclo[8]pyrroles

Cited by 8 publications

References 12 publications

Figure Eights, Möbius Bands, and More: Conformation and Aromaticity of Porphyrinoids

Figure Eights, Möbius Bands, and More: Conformation and Aromaticity of Porphyrinoids

Low-cost laparoscopic cholecystectomy (Br J Surg 2002; 89: 1602–1607)

A Macrocyclic Furan with Accessible Oxidation States: Switching Between Aromatic and Antiaromatic Global Ring Currents

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