Synthesis and Chiroptical Properties of Binaphthyl‐Hinged [5]Helicenes

Hasegawa, Masashi; Nojima, Yuki; Nagata, Yuuya; Usui, Kazuteru; Sugiura, Ken‐ichi; Mazaki, Yasuhiro

doi:10.1002/ejoc.202300656

Cited by 11 publications

(3 citation statements)

References 46 publications

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“…Recently, we synthesized chiral macrocycles 37a,b, in which helicenes were combined with tethered binaphthyl, based on the fact that binaphthyl induces chirality (Figure 14). 85 [5]-Helicene slowly racemizes at room temperature. 86,87 In 2004, Marinetti et al reported that a chiral 1,3pentandiol tether at the end of [5]-helicene prevents epimerization and induces chirality in the helicene moiety.…”

Section: Binaphthyl-hinged [5]-helicenementioning

confidence: 99%

Stereogenic π-Conjugated Macrocycles: Synthesis, Structure, and Chiroptical Properties Including Circularly Polarized Luminescence

Hasegawa,

Mazaki

2023

Synlett

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Highly symmetrical and aesthetically pleasing molecules have attracted the attention of organic chemists. We synthesized new highly symmetric stereogenic π-conjugated macrocycles with planar or axial chirality. Macrocyclic oligomers synthesized by Yamamoto coupling or Suzuki–Miyaura cross-coupling from the π-unit containing chirality. These cyclization reactions gave multiple oligomers in relatively high yields. We then elucidated their structures and investigated their chiroptical properties, including circular dichroism (CD) and circularly polarized luminescence (CPL). Because of the selection rule for rigid and symmetric structures, these macrocycles exhibit a high dissymmetry factor (g abs or g lum) for circularly polarized light in CD or CPL. Several rigid cyclic compounds retain a highly symmetric structure in the excited state and exhibit higher g lum values than common chiral organic compounds. This Account provides a brief background regarding chiroptical properties, followed by a summary of the various macrocycles synthesized in this study. We are glad if this Account will be a source of ideas not only for chemists working with π-conjugated compounds, but also for synthetic chemists working with chiral compounds, especially those engaged in asymmetric synthesis.1 Introduction2 Brief Description of Chiroptical Properties3 Stereogenic Macrocycle Based on [2.2]Paracyclophane3.1 Stereogenic Double-decker Oligothiophene3.2 Stereogenic Biselenophene Macrocycle3.3 Helical Oligophenylene Linked with [2.2]Paracyclophane4 Stereogenic Macrocycle Based on Binaphthyl4.1 Cyclic Oligomer of Chiral Binaphthyl4.2 Doubly Twisted Binaphthyl Dimer4.3 Cyclic Oligomer of Binaphthyl Extended with Paraphenylene4.4 Curved Helical Paraphenylene Anchoring Chiral Binaphthyl4.5 Binaphthyl-Hinged [5]-Helicene5 Summary

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Section: Binaphthyl-hinged [5]-helicenementioning

confidence: 99%

Stereogenic π-Conjugated Macrocycles: Synthesis, Structure, and Chiroptical Properties Including Circularly Polarized Luminescence

Hasegawa,

Mazaki

2023

Synlett

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“…Effective strategies to overcome this limitation include converting the naphthalene ring to a larger  system, such as a pyrene ring [12][13][14] , and enhancing the  system by introducing a phenylethynyl group onto the naphthalene ring [15] . Recently, many studies on the use of compounds linked to the binaphthyl skeleton as chiral luminescent molecules, including molecules with circularly polarized luminescence (CPL), have been reported [16][17][18][19][20] . In this study, a series of compounds (denoted 3-PE to 8-PE) was synthesized, involving the bridging of the two hydroxy groups of 1,1ʹ-bi-2-naphthol (BINOL) by a methylene unit (i.e., one carbon atom) and the incorporation of two phenylethynyl groups at all of the feasible substitution positions.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Functions of Binaphthyl Derivatives with Comprehensive Introduction of Phenylethynyl Groups

Sakai,

Imayoshi,

Sasamori

et al. 2024

Preprint

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In this study, compounds with phenylethynyl (PE) groups introduced at all of the possible positions of the methylene-bridged structure of the 1,1ʹ-bi-2-naphthol backbone (3-PE to 8-PE) were synthesized. Compounds with four or six phenylethynyl groups (3,6-PE, 4,6-PE, 5,6-PE, 6,7-PE, and 3,4,6-PE) were also synthesized. The key reaction for the synthesis of these compounds was the Sonogashira reaction using halogen scaffolds. The new transformation methods include (1) selective bromination of the 5-position of the binaphthyl skeleton and (2) bromination of the 6-position and then iodination of the 4-position, followed by the Sonogashira reaction of iodine at the 4-position and lithiation and protonation of bromine at the 6-position. The optical properties of the compounds were evaluated. The extension of the π system greatly differed depending on the position of the phenylethynyl group. 4-PE, 4,6-PE, and 3,4,6-PE, in which the phenylethynyl groups were introduced in the extended direction of the naphthalene linkage axis, showed longer absorption and emission wavelengths and higher fluorescence quantum yields than the other compounds. In circularly polarized luminescence measurements, 7-PE showed a relatively large glum value, an interesting finding that reverses the sense.

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“…[15] Recently, many studies on the use of compounds linked to the binaphthyl skeleton as chiral luminescent molecules, including molecules with circularly polarized luminescence (CPL), have been reported. [16][17][18][19][20] In this study, a series of compounds (denoted 3-PE to 8-PE) was synthesized, involving the bridging of the two hydroxy groups of 1,1'-bi-2-naphthol (BINOL) by a methylene unit (i. e., one carbon atom) and the incorporation of two phenylethynyl groups at all of the feasible substitution positions. Subsequently, compounds possessing four or six phenylethynyl groups (3,6-PE, 4,6-PE, 5,6-PE, 6,7-PE, and 3,4,6-PE) were also synthesized, and their optical properties were systematically evaluated (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Optical Properties of Binaphthyl Derivatives with Comprehensive Introduction of Phenylethynyl Groups

Sakai,

Fujio,

Imayoshi

et al. 2024

Chemistry An Asian Journal

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In this study, compounds with phenylethynyl (PE) groups introduced at all of the possible positions of the methylene‐bridged structure of the 1,1ʹ‐bi‐2‐naphthol backbone (3‐PE to 8‐PE) were synthesized. Compounds with four or six phenylethynyl groups (3,6‐PE, 4,6‐PE, 5,6‐PE, 6,7‐PE, and 3,4,6‐PE) were also synthesized. The key reaction for the synthesis of these compounds was the Sonogashira reaction using halogen scaffolds. The new transformation methods include (1) selective bromination of the 5‐position of the binaphthyl skeleton and (2) bromination of the 6‐position and then iodination of the 4‐position, followed by the Sonogashira reaction of iodine at the 4‐position and lithiation and protonation of bromine at the 6‐position. The optical properties of the compounds were evaluated. The extension of the π system greatly differed depending on the position of the phenylethynyl group. 4‐PE, 4,6‐PE, and 3,4,6‐PE, in which the phenylethynyl groups were introduced in the extended direction of the naphthalene linkage axis, showed longer absorption and emission wavelengths and higher fluorescence quantum yields than the other compounds. In circularly polarized luminescence measurements, 7‐PE showed a relatively large glum value, an interesting finding that reverses the sense.

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Synthesis and Chiroptical Properties of Binaphthyl‐Hinged [5]Helicenes

Cited by 11 publications

References 46 publications

Stereogenic π-Conjugated Macrocycles: Synthesis, Structure, and Chiroptical Properties Including Circularly Polarized Luminescence

Stereogenic π-Conjugated Macrocycles: Synthesis, Structure, and Chiroptical Properties Including Circularly Polarized Luminescence

Synthesis and Functions of Binaphthyl Derivatives with Comprehensive Introduction of Phenylethynyl Groups

Synthesis and Optical Properties of Binaphthyl Derivatives with Comprehensive Introduction of Phenylethynyl Groups

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