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Synlett 2018; 29(16): 2147-2154
DOI: 10.1055/s-0037-1610190
cluster
© Georg Thieme Verlag Stuttgart · New York

Transmission of Point Chirality to Axial Chirality for Strong Circular Dichroism in Triarylmethylium-o,o-dimers

Yusuke Ishigaki 
a   Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan   Email: tak@sci.hokudai.ac.jp
,
Tomohiro Iwai
a   Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan   Email: tak@sci.hokudai.ac.jp
,
Yuki Hayashi
a   Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan   Email: tak@sci.hokudai.ac.jp
,
Aiichiro Nagaki
b   Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
,
Ryo Katoono
a   Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan   Email: tak@sci.hokudai.ac.jp
,
Kenshu Fujiwara
c   Department of Life Science, Graduate School of Engineering Science, Akita University, Akita 010-8052, Japan
,
Jun-ichi Yoshida
b   Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
,
Takanori Suzuki  *
a   Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan   Email: tak@sci.hokudai.ac.jp
› Author AffiliationsThis work was also supported by the Research Program of the “Five-star Alliance” in “NJRC Mater. & Dev.” MEXT. We thank Grant-in-Aid for Scientific Research on Innovative Areas: “Middle molecular strategy” (No. 2707) and “Reaction Integration” (No. 2105) from MEXT and Grant-in-Aid from JSPS (Nos. 15H03790, 16K13968, 18K05069) Japan.
Further Information

Publication History

Received: 02 May 2018

Accepted after revision: 24 May 2018

Publication Date:
25 June 2018 (online)

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In memory of Kurt Mislow (1923–2017) and Shô Itô (1924–2018)

Published as part of the Cluster Atropisomerism

Abstract

Triarylmethylium-o,o-dimers adopt a twisted geometry so that two diarylmethyliums are stacked in a slipped manner. Thus, chiral auxiliaries on the aryl groups induce a preference in the axial chirality of the central biphenyl unit. Strong circular dichroism is attained through exciton coupling, which can be used for additional spectral output in their electrochromic behavior. Diastereoselectivity based on π–π stacking exhibits unique solvent effects, thus endowing multifunctional response properties.

Key words

chiral induction - axial chirality - exciton coupling - redox system - electrochromism - flow microreactor - dication - dye

Supporting Information

    The experimental procedures and characterization data for new compounds are given in the Supporting Information. The cyclic voltammogram of (R,R,R,R)-5 2+ in CH2Cl2, VT-NMR spectra of (R,R)-6 2+(SbCl6 −)2 in CDCl3, and CD spectra of (R,R)-6 2+(SbCl6 −)2 and the related dication salts in various solvents are also given.

    Supporting information for this article is available online at https://doi.org/10.1055/s-0037-1610190.
  • Supporting Information
 

  • References and Notes

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  • 11 Experimental procedures and characterization data for new compounds are given in the Supporting Information. Selected analytical data are as follows: (R,R,R,R)-5: Mp 83–86 °C (decomp.). IR (KBr): 2928, 2856, 1608, 1574, 1556, 1460, 1434, 1376, 1280, 1197, 1160, 1110, 1030, 917, 849, 598 cm–1. 1H NMR (300 MHz, CD3CN): δ = 6.73–7.84 (24 H, brm), 4.79 (4 H, m), 1.75 (8 H, brm), 1.24–1.57(44 H, brm), 0.83–1.83 (12 H, brm) ppm. 13C NMR (75 MHz, CDCl3): δ = 190.85, 190.59, 173.70, 173.68, 171.03, 170.85, 146.18, 144.28, 144.17, 142.69, 142.56, 140.63, 136.64, 136.55, 134.18, 134.14, 133.83, 133.81, 133.21, 132.92, 131.88, 131.85, 128.2259, 119.14, 118.33, 118.25, 79.29, 79.19, 77.72, 77.48, 36.35, 36.27, 36.26, 36.20, 32.10, 32.08, 32.05, 29.43, 25.51, 25.49, 25.44, 22.91, 19.76, 19.57, 19.47, 13.98 ppm. FAB-LR-MS: m/z = 997 ([M – 2SbCl6]+, 15%). UV/Vis (CH2Cl2): λmax = 538 (log ε 5.00), 417 (4.57), 280 (4.63) nm. CD (CH2Cl2): λ = 564 (Δε +31), 534 (–19), 406 (+2.9), 281 (–4.6), 267 (+1.5) nm. Anal. Calcd for C70H92Cl12O4Sb2: C, 50.45; H, 5.56; Cl, 25.53. Found: C, 50.43; H, 5.31; Cl, 25.45. (R,R,R,R)-5 2+(SbCl6 −)2: Mp 83–86 °C (decomp.). IR (KBr) 2928, 2856, 1608, 1574, 1556, 1460, 1434, 1376, 1280, 1197, 1160, 1110, 1030, 917, 849, 598 cm–1. 1H NMR (300 MHz, CD3CN): δ = 6.73–7.84 (24 H, brm), 4.79 (4 H, m), 1.75 (8 H, brm), 1.24–1.57(44 H, brm), 0.83–1.83 (12 H, brm) ppm. 13C NMR (75 MHz, CDCl3):δ = 190.85, 190.59, 173.70, 173.68, 171.03, 170.85, 146.18, 144.28, 144.17, 142.69, 142.56, 140.63, 136.64, 136.55, 134.18, 134.14, 133.83, 133.81, 133.21, 132.92, 131.88, 131.85, 128.2259, 119.14, 118.33, 118.25, 79.29, 79.19, 77.72, 77.48, 36.35, 36.27, 36.26, 36.20, 32.10, 32.08, 32.05, 29.43, 25.51, 25.49, 25.44, 22.91, 19.76, 19.57, 19.47, 13.98 ppm. FAB-LR-MS: m/z = 997 ([M – 2SbCl6]+, 15%). UV/Vis (CH2Cl2): λmax = 538 (log ε 5.00), 417 (4.57), 280 (4.63) nm. CD (CH2Cl2): λ = 564 (Δε +31), 534 (–19), 406 (+2.9), 281 (–4.6), 267 (+1.5) nm. Anal. Calcd for C70H92Cl12O4Sb2: C, 50.45; H, 5.56; Cl, 25.53. Found: C, 50.43; H, 5.31; Cl, 25.45. (R,R,R,R)-7: IR (neat): 3406, 2930, 2857, 1606, 1505, 1465, 1376, 1291, 1244, 1175, 1114, 829, 756, 665 cm–1. 1H NMR (300 MHz, CDCl3): δ = 6.99–7.26 (10 H, m), 6.75–6.83 (12 H, m), 6.07 (2 H, d, J = 7.3 Hz), 4.41 (2 H, s), 4.30–4.36 (4 H, m, J = 6.0 Hz), 1.16–1.82 (52 H, brm), 0.88 (12 H, brm) ppm. 13C NMR (75 MHz, CDCl3): δ = 157.27, 157.07, 144.07, 140.87, 140.58, 138.38, 131.56, 130.24, 129.72, 128.56, 125.84, 125.79, 115.05, 114.89, 83.22, 74.00, 73.82, 36.43, 31.81, 29.28, 25.52, 22.59, 19.73, 14.07 ppm. FD-LR-MS: m/z = 1030 (M+, BP). FD-HR-MS: m/z calcd for C70H94O6: 1030.7050; found: 1030.7045. (R,R)-6: Mp 138–142 °C (decomp.). IR (KBr): 3042, 2929, 2856, 2799, 1608, 1576, 1505, 1480, 1443, 1376, 1353, 1286, 1247, 1213, 1186, 1125, 1062, 1013, 948, 848, 807, 759, 746, 619, 573 cm–1. 1H NMR (300 MHz, C6D6): δ = 7.68–7.63 (3 H, m), 7.59 (1 H, dd, J = 7.9, 1.4 Hz), 7.45 (4 H, br), 7.38 (4H, br), 7.13–7.02 (4 H, m), 6.64 (4 H, brd, J = 7.9 Hz), 6.31 (4 H, brd, J = 7.9 Hz), 4.03 (2 H, br), 2.42 (12 H, s), 1.68–1.52 (2 H, m), 1.39–1.01 (24 H, m), 0.86 (6 H, t, J = 6.9 Hz) ppm. 13C NMR (100 MHz, C6D6): δ = 156.73, 148.57, 145.79, 145.34, 136.84, 136.64, 129.17, 129.05, 127.90, 127.00, 126.83, 124.68, 124.54, 112.65, 110.03, 73.11, 63.91, 63.65, 39.94, 36.94, 36.88, 32.10, 29.64, 25.80, 22.94, 19.88, 19.85, 14.30 ppm. FD-LR-MS: m/z = 829 (34), 828 (80), 827 (M+, BP). FD-HR-MS: m/z calcd for C58H70N2O2: 826.5437; found: 826.5437. UV/Vis (CH2Cl2): λmax = (log ε) 270 (4.61) nm. (R,R)-6 2+(SbCl6 −)2: Mp 128–132 °C. IR (KBr): 3061, 2927, 2856, 1618, 1606, 1582, 1485, 1464, 1435, 1362, 1315, 1278, 1159, 1109, 1029, 963, 937, 910, 850, 831, 755, 722, 600 cm–1. 1H NMR (300 MHz, CDCl3): δ = 6.60–8.00 (24 H, brm), 4.72–4.88 (2 H, brm), 3.25 (12 H, m), 1.66–1.90 (4 H, brm), 1.18–1.56 (22 H, brm), 0.87–1.02 (6 H, brm) ppm. 13C NMR (100 MHz, CDCl3): δ = 19.38, 19.45, 19.55, 25.35, 25.47, 29.40, 29.48, 29.49, 32.05, 32.1065, 36.13, 36.18, 36.27, 40.81, 41.36, 41.44, 77.45, 77.61, 78.70, 78.71, 113.92, 114.77, 118.66, 127.24, 127.81, 127.88, 130.70, 130.79, 132.47, 132.52, 132.99, 133.47, 133.64, 133.85, 133.94, 134.17, 136.52, 136.63, 138.98, 140.24, 140.30, 140.38, 140.41, 141.21, 141.26, 142.29, 142.41, 143.08, 143.17, 145.37, 145.39, 157.82, 157.98, 170.95, 172.78, 173.00, 191.52, 191.71 ppm. FD-LR-MS: m/z = 8277 ([M – 2SbCl6]+, BP). FD-HR-MS: m/z calcd for C58H70N2O2: 826.5437; found: 826.5420. (R,R)-8: Mp 71.0–74.0 °C. IR (KBr): 3411, 2929, 2856, 2800, 1609, 1505, 1466, 1443, 1376, 1351, 1293, 1243, 1162, 1132, 1062, 1132, 1004, 948, 917, 816, 759, 622, 577, 560 cm–1. 1H NMR (300 MHz, CDCl3): δ = 7.10–6.98 (8 H, m), 6.95 (2 H, d, J = 9.0 Hz), 6.86–6.80 (3 H, m), 6.79–6.73 (5 H, m), 6.63 (4 H, dd, J = 9.0, 1.5 Hz), 6.19 (1 H, d, J = 7.7 Hz), 6.03 (1 H, d, J = 7.7 Hz), 5.17 (1 H, brd, J = 7.9 Hz), 4.39–4.26 (2 H, m), 3.63 (1 H, brd, J = 4.8 Hz), 2.95 (6 H, s), 2.91 (6 H, s) 1.72 (2 H, br), 1.50–1.22 (24 H, m), 0.92–0.83 (6 H, m) ppm. 13C NMR (100 MHz, CDCl3): δ = 157.07, 156.82, 149.56, 149.40, 144.50, 144.03, 141.39, 141.17, 140.71, 138.52, 136.86, 134.69, 131.58, 131.41, 130.28, 130.20, 129.67, 129.37, 128.62, 128.11, 125.92, 125.72, 125.44, 125.39, 114.93, 114.83, 111.73, 111.69, 83.86, 82.64, 82.59, 73.97, 73.92, 73.76, 40.62, 40.55, 36.51, 36.47, 36.37, 31.80, 29.28, 29.25, 25.53, 25.48, 22.57, 19.77, 19.67, 14.06 ppm. FD-LR-MS: m/z = 863 (22), 862 (63), 861 (M+, BP), 844 (24), 843 (35). FD-HR-MS: m/z calcd for C58H72N2O4: 860.5492; found: 860.5485.
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