Synlett 2015; 26(04): 489-493
DOI: 10.1055/s-0034-1379549
letter
© Georg Thieme Verlag Stuttgart · New York

Synthesis of a ‘Propeller-Like’ Oligoheteroaryl with Alternating Pyridine and Oxazole Motifs

Savvas N. Georgiades*
Department of Chemistry, University of Cyprus, 1 Panepistimiou Ave., Aglandjia, Nicosia 2109, Cyprus   Fax: +357(22)895456   Email: georgiades.savvas@ucy.ac.cy
,
Natalia Rizeq
Department of Chemistry, University of Cyprus, 1 Panepistimiou Ave., Aglandjia, Nicosia 2109, Cyprus   Fax: +357(22)895456   Email: georgiades.savvas@ucy.ac.cy
› Author Affiliations
Further Information

Publication History

Received: 14 October 2014

Accepted after revision: 24 October 2014

Publication Date:
08 January 2015 (online)


Abstract

The molecular architecture of oligomeric pyridyl-oxazole compounds is key to determining their mode of interaction with G-quadruplex DNA structures, which is a family of prominent anticancer biomolecular targets. We report herein an efficient synthetic route that begins with chelidamic acid and affords, in just seven steps, an unusual ‘propeller-like’ pyridyl-oxazole architecture with alternating pyridine and oxazole rings, that has not been yet validated as a G-quadruplex binder. The synthesis employs Van Leusen chemistry for the construction of oxazole rings from aldehydes, and two Pd(II)/Cu(I)-mediated cross-coupling reactions involving C–H activation of oxazoles for the formation of C–C bonds between bromopyridine intermediates and oxazole fragments. This modular synthesis was designed to be amenable to the construction of analogues.

Supporting Information

 
  • References and Notes

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  • 9 Data for compound 2: 1H NMR (CDCl3): δ = 1.41 (t, J = 7.1 Hz, 6 H), 4.46 (q, J = 7.1 Hz, 4 H), 7.35 (s, 2 H). 13C NMR (CDCl3 + trace DMSO-d 6): δ = 13.6, 61.6, 115.6, 148.1, 163.9, 167.1. MS (ESI): m/z = 238.08 (calcd 238.07 [M – H]), 261.06 (calcd 261.06, [M + Na – H]).
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  • 12 Data for compound 4: 1H NMR (CDCl3): δ = 7.13 (t, J =7.0 Hz, 1 H), 7.55 (d, J = 7.0 Hz, 1 H), 7.61 (s, 1 H), 7.65 (t, J = 7.0 Hz, 1 H), 7.89 (s, 1 H), 8.53 (d, J = 7.0 Hz, 1 H). 13C NMR (CDCl3): δ = 119.0, 122.7, 124.5, 136.6, 146.7, 149.5, 150.7, 150.8. MS (ESI): m/z = 147.06 (calcd 147.06, [M + H]+).
  • 13 Data for compound 5: 1H NMR (CDCl3): δ = 1.46 (t, J = 7.2 Hz, 6 H), 4.51 (q, J = 7.2 Hz, 4 H), 7.29 (td, J 1 = 5.5 Hz, J 2=2.8 Hz, 1 H), 7.80–7.82 (m, 2 H, overlapping), 7.90 (s, 1 H), 8.65 (dt, J 1 = 4.7 Hz, J 2 = 1.5 Hz, 1 H), 8.87 (s, 2 H). 13C NMR (CDCl3): δ = 14.1, 62.5, 119.7, 123.6, 123.8, 127.6, 136.5, 137.0, 146.2, 149.6, 150.0, 152.5, 158.0, 164.0. MS (ESI): m/z = 368.12 (calcd 368.13, [M + H]+).
  • 16 Data for compound 6: 1H NMR (DMSO-d 6): δ = 4.63 (d, J = 6.1 Hz, 4 H), 5.63 (t, J = 6.1 Hz, 2 H), 7.44 (t, J = 5.8 Hz, 1 H), 7.96–7.98 (m, 4 H, overlapping), 8.06 (s, 1 H), 8.69 (d, J = 5.0 Hz, 1 H). 13C NMR (DMSO-d 6): δ = 64.1, 114.2, 119.9, 123.9, 127.4, 134.4, 137.6, 146.1, 150.1, 151.5, 159.7, 162.8. MS (ESI): m/z = 282.10 (calcd 282.09, [M – H]).
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  • 21 Data for compound 8: 1H NMR (CDCl3): δ = 7.31 (t, J = 5.6 Hz, 1 H), 7.83–7.87 (m, 4 H, overlapping), 7.93 (s, 1 H), 8.05 (s, 2 H), 8.26 (s, 2 H), 8.69 (d, J = 4.5 Hz, 1 H). 13C NMR (CDCl3 + trace CD3OD): δ = 114.0, 114.8, 119.9, 123.6, 126.3, 127.5, 131.4, 136.1, 137.2, 146.5, 148.3, 150.1, 152.2, 158.9. MS (ESI): m/z = 358.10 (calcd 358.10, [M + H]+).
  • 22 Data for compound 10: 1H NMR (CDCl3): δ = 7.33 (dd, J 1 =7.9, J 2 = 4.9 Hz, 1 H), 7.45 (dd, J 1 = 7.9, J 2 = 4.9 Hz, 2 H), 7.85–7.95 (m, 3 H, overlaid), 7.95 (d, J = 6.5 Hz, 1 H), 7.96 (s, 1 H), 8.08 (s, 2 H), 8.30 (d, J = 7.9 Hz, 2 H), 8.49 (s, 2 H), 8.72 (d, J = 4.9 Hz, 1 H), 8.83 (d, J = 4.1 Hz, 2 H). 13C NMR (CDCl3): δ = 115.1, 120.0, 122.7, 123.6, 125.1, 127.6, 128.8, 136.2, 137.0, 137.2, 145.8, 146.7, 148.3, 149.0, 150.2, 151.2, 152.5, 159.1, 161.2. MS (ESI): m/z = 512.14 (calcd 512.15, [M + H]+).