Mechanistic Consideration for the Selective Inclusion of Disubstituted Benzene Isomers with p-tert-Butylcalix[4]arene Crystals

The nematic twist-bend (NTB) liquid crystal phase possesses a local helical structure with a pitch length of a few nanometres and is the first example of spontaneous symmetry breaking in a fluid system. All known examples of the NTB phase occur in materials whose constituent mesogenic units are aromatic hydrocarbons. It is not clear if this is due to synthetic convenience or a bona fide structural requirement for a material to exhibit this phase of matter. In this work we demonstrate that materials consisting largely of saturated hydrocarbons could also give rise to this mesophase. Furthermore, replacement of 1,4-disubstituted benzene with trans 1,4-cyclohexane or even 1,4-cubane does not especially alter the transition temperatures of the resulting material nor does it appear to impact upon the heliconical tilt angle, suggesting the local structure of the phase is unperturbed. Calculating the probability distribution of bend angles reveals that the choice of isosteric group has little impact on the overall molecular shape, demonstrating the shape-driven nature of the NTB phase.

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On the superimposability of the electronic spectra of disubstituted benzene derivatives in the interpretation of the principal absorption bands of certain trisubstituted derivatives

Recueil des Travaux Chimiques des Pays-Bas ◽

10.1002/recl.19630820408 ◽

2010 ◽

Vol 82 (4) ◽

pp. 361-369

Author(s):

R. F. Rekker ◽

W. Th. Nauta

Keyword(s):

Electronic Spectra ◽

Benzene Derivatives ◽

Absorption Bands ◽

Disubstituted Benzene

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Inter-relationships between the CCC bond angles in the ring in monosubstituted and para-disubstituted benzene derivatives, and between the CC bond lengths: A molecular study

Journal of Molecular Structure THEOCHEM ◽

10.1016/0166-1280(86)80133-6 ◽

1986 ◽

Vol 137 (3-4) ◽

pp. 387-390 ◽

Cited By ~ 8

Author(s):

Philip George ◽

Charles W. Bock ◽

Mendel Trachtman

Keyword(s):

Molecular Study ◽

Benzene Derivatives ◽

Bond Angles ◽

Bond Lengths ◽

Disubstituted Benzene

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Zhaoshumycins A and B, Two Unprecedented Antimycin-Type Depsipeptides Produced by the Marine-Derived Streptomyces sp. ITBB-ZKa6

Marine Drugs ◽

10.3390/md19110624 ◽

2021 ◽

Vol 19 (11) ◽

pp. 624

Author(s):

Zhikai Guo ◽

Shiying Ma ◽

Salman Khan ◽

Hongjie Zhu ◽

Bo Zhang ◽

...

Keyword(s):

Toxicity Tests ◽

Marine Actinomycetes ◽

Human Breast ◽

Mcf7 Cells ◽

Imino Group ◽

Streptomyces Sp ◽

New Class ◽

Relationship Analysis ◽

Disubstituted Benzene ◽

New Compounds

Marine actinomycetes are prolific chemical sources of complex and novel natural products, providing an excellent chance for new drug discovery. The chemical investigation of the marine-derived Streptomyces sp. ITBB-ZKa6, from Zhaoshu island, Hainan, led to the discovery of two unique antimycin-type depsipeptides, zhaoshumycins A (1) and B (2), along with the isolation of the four known neoantimycins A (3), F (4), D (5), and E (6). The structures of the new compounds 1 and 2 were elucidated on the basis of the analysis of diverse spectroscopic data and biogenetic consideration. Zhaoshumycins A (1) and B (2) represent a new class of depsipeptides, featuring two neoantimycin monomers (only neoantimycin D or neoantimycins D and E) linked to a 1,4-disubstituted benzene ring via an imino group. Initial toxicity tests of 1–6 in MCF7 human breast cancer cells revealed that compounds 5 and 6 possess weak cytotoxic activity. Further structure–activity relationship analysis suggested the importance of the NH2 group at C-34 in 5 and 6 for cytotoxicity in MCF7 cells.

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Macrocyclization Using RCM Reactions. Synthesis of Simple Metacyclophanes and Synthetic Efforts toward Platycarynol, a 15-Membered Aromatic Ether

Natural Product Communications ◽

10.1177/1934578x1601100826 ◽

2016 ◽

Vol 11 (8) ◽

pp. 1934578X1601100

Author(s):

Katsuyuki Nakashima ◽

Hatsuna Matsunaga ◽

Masako Ito ◽

Hiroshi Minami ◽

Akihito Aiba ◽

...

Keyword(s):

Ground State ◽

Diphenyl Ether ◽

Benzene Derivatives ◽

Disubstituted Benzene ◽

Aromatic Ether

Preparation of 13- to 19-membered carbocycles (metacyclophanes) from 1,3-disubstituted benzene derivatives has been successfully carried out using the RCM reaction, but similar starting materials having diphenyl ether did not cyclize to 15-membered compounds, whose ground state conformations were calculated and discussed. Several attempts to cyclize to form platycarynol are described.

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