The synthesis and crystal structure of pH-sensitive fluorescent pyrene-based double aza- and diaza[4]helicenes

Tonkoglazova, Daria I.; Oryabinskaya, Lyubov M; Shcherbatykh, A. A.; Gulevskaya, A. V.

doi:10.1039/d2ob00204c

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References 87 publications

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“…The same methodology has been applied for the synthesis of azine-fused [4]-, [53,54] [5]- [55] and [6]helicenes [56] 16-21, including double S-shaped [4]helicenes 18 [54] and 19 [57] (Scheme 3). The starting ortho-alkynylated heterobiaryls 12 were synthesized from commercially available 2,3-dihaloazines 11 through subsequent Sonogashira reaction and Suzuki arylation or vice versa.…”

Section: Electrophile-induced Cyclizations Of Ortho-alkynylated Biarylsmentioning

confidence: 99%

Alkyne‐Based Syntheses of Carbo‐ and Heterohelicenes

Gulevskaya

Tonkoglazova

2022

Adv Synth Catal

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[n]Helicenes are polycyclic aromatic molecules in which n ortho‐condensed benzene or other aromatic rings give rise to helical chiral and highly conjugated structures. The unique screw shape, helically extended π‐system and intriguing electronic and chirooptical properties of these molecules have attracted scientific interest for decades. The applications of helicenes have now expanded into several fields including material science, nanoscience, biochemistry, supramolecular and polymer chemistry. Despite the great theoretical and practical interest in helicenes, their synthesis remains a challenge. Among synthetic approaches to helicenes, alkyne cyclizations have great potential, since carbon‐rich high‐energy alkynes can form aromatic rings via cycloisomerizations. These processes are atom‐economic. In addition, alkyne reactions are highly favorable thermodynamically. This review focuses on alkyne‐based syntheses of carbo‐ and heterohelicenes (2000–2022). These syntheses are obviously multistage. In the review, they are systematized in terms of the key step leading to the formation of a helical shape. The methods are grouped into two categories: (a) metal‐free syntheses and (b) transition‐metal‐catalyzed syntheses. This division is very arbitrary, since catalytic Sonogashira and Suzuki‐Miyaura reactions and others are often used to prepare starting materials in the syntheses of the first group. Most of the publications on the topic are related to transition‐metal‐catalyzed syntheses of helicenes.

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