G. Brackman et al. / Bioorg. Med. Chem. 20 (2012) 4737–4743
4741
acyl-chain compounds affected 3-oxo-C12-HSL-based QS. Altering
the acyl-side chain by phenyl-compounds resulted in active mod-
ulators of QS in both systems. Finally, the most active QSI exhibited
strong inhibitory and eradicating activities against B. cenocepacia
and P. aeruginosa biofilms.
1.63–1.73 (m, 2H, H-5), 1.31–1.37 (m, 4H, H-6 and H-7), 0.87–0.91
(m, 3H, H-8); 13C NMR (75 MHz, CDCl3): d 171.4, 149.4, 120.9,
66.6, 57.7, 31.6, 29.5, 29.2, 25.8, 22.6, 14.2; ESI-MS for C11H17N3O2
[MÀH]+, Found, 224.1387; Calcd, 224.1394 (Supplementary data).
4.2.5. 3c: 3-(4-Hexyl-1H-1,2,3-triazol-1yl)dihydrofuran-2(3H)-
one
4. Materials and methods
1H NMR (300 MHz, CDCl3): d 7.53 (s, 1H, triazole H), 5.30 (t, 1H,
J = 9.4 Hz, H-3), 4.63–4.70 (m, 1H, H-1), 4.48 (dt, 1H, J = 6.8 Hz and
9.0 Hz, H-1), 2.91–3.10 (m, 2H, H-2), 2.72 (t, 2H, J = 7.8 Hz, H-4),
1.61–1.71 (m, 2H, H-5), 1.24–1.40 (m, 6H, H-6, H-7 and H-8), 0.87
(t, 3H, J = 6.9 Hz, H9); 13C NMR (75 MHz, CDCl3): d 171.3, 149.3,
120.9, 66.5, 57.6, 31.7, 29.5, 29.4, 29.1, 25.8, 22.7, 14.2; ESI-MS for
4.1. Strains and culture conditions
E. coli JB52323 was grown aerobically on Luria Bertani (LB) agar
(BD, Sparks, MD) supplemented with 100 lg/ml tetracycline and
0.4% NaCl. The QS inhibition selector P. aeruginosa QSIS224 was cul-
tured aerobically in ABT minimal medium (AB medium, containing
2.5 mg/l of thiamine) supplemented with 0.5% glucose, 0.5% casa-
C
12H19N3O2 [MÀH]+, Found, 238.1563; Calcd, 238.1550 (Supple-
mentary data).
mino acids and 80 lg/ml gentamicin. B. cenocepacia LMG16656
4.2.6. 3d: 3-(4-Heptyl-1H-1,2,3-triazol-1yl)dihydrofuran-2(3H)-
one
and P. aeruginosa PAO1 were cultured aerobically on tryptone soy
agar (Oxoid, Hampshire, UK) or in Mueller Hinton medium (Oxoid).
All strains were grown at 37 °C, with the exception of E. coli JB523
(30 °C).
1H NMR (300 MHz, CDCl3): d 7.53 (s, 1H, triazole H), 5.30 (t, 1H,
J = 9.2 Hz, H-3), 4.64–4.71 (m, 1H, H-1), 4.49 (dt, 1H, J = 6.8 Hz and
9.1 Hz, H-1), 2.91–3.11 (m, 2H, H-2), 2.72 (t, 2H, J = 7.8 Hz, H-4),
1.67 (quintet, 2H, J = 7.5 Hz, H-5), 1.28–1.38 (m, 8H, H-6, H-7, H-
8 and H-9), 0.87 (t, 3H, J = 6.9 Hz, H-10); 13C NMR (75 MHz, CDCl3):
d 171.3, 149.3, 120.8, 66.5, 57.6, 31.9, 29.5, 29.4, 29.2, 25.8, 22.8,
14.2; ESI-MS for C13H21N3O2 [MÀH]+, Found, 252.1719; Calcd,
252.1707 (Supplementary data).
4.2. General procedure for the synthesis of 2 and 3a–j
4.2.1. 3-Azidodihydrofuran-2(3H)-one (2)
a-Bromo-c-butyrolactone (1) (925 ll, 10 mmol, 1 equiv) was
dissolved in acetone (17 ml) and a solution of NaN3 (3.25 g in
7 ml H2O, 50 mmol, 5 equiv) was added. The resulting solution
was stirred overnight. Acetone was removed by evaporation under
reduced pressure. The resulting aqueous mixture was extracted
with CH2Cl2 (2 Â 50 mL) and the organic layers were combined,
dried over Na2SO4, filtered, and evaporated under reduced pres-
sure. The resulting oil was found to be pure by NMR analysis
(and was used without further purification). 1H NMR (300 MHz,
CDCl3): d 4.42 (dt, 1H, J = 3.6 Hz and 8.9 Hz, H-3), 4.23–4.31 (m,
2H, H-3 and H-1), 2.50–2.61 (m, 1H, H-2), 2.10–2.24 (m, 1H, H-
2); 13C NMR (75 MHz, CDCl3): d 173.6, 66.0, 56.8, 29.1
4.2.7. 3e: 3-(4-Octyl-1H-1,2,3-triazol-1yl)dihydrofuran-2(3H)-
one
1H NMR (300 MHz, CDCl3): d 7.53 (s, 1H, triazole H), 5.29 (t, 1H,
J = 9.2 Hz, H-3), 4.64–4.71 (m, 1H, H-1), 4.49 (dt, 1H, J = 6.8 Hz and
9.1 Hz, H-1), 2.93–3.12 (m, 2H, H-2), 2.73 (t, 2H, J = 7.8 Hz, H-4),
1.67 (quintet, 2H, J = 7.5 Hz, H-5), 1.25–1.38 (m, 10H, H-6, H-7,
H-8, H-9 and H-10), 0.87 (t, 3H, J = 6.8 Hz, H-11); 13C NMR
(75 MHz, CDCl3): d 171.2, 149.3, 120.8, 66.5, 57.6, 32.0, 29.47,
29.45, 29.44, 29.41, 29.3, 25.8, 22.8, 14.2; ESI-MS for C14H23N3O2
[MÀH]+, Found, 266.1877; Calcd, 266.1863 (Supplementary data).
4.2.2. General procedure for the synthesis of 3a–j
4.2.8. 3f: 3-(4-Decyl-1H-1,2,3-triazol-1yl)dihydrofuran-2(3H)-
one
To a solution of 2 (1 equiv) in a mixture of t-BuOH:H2O, a 0.1 M
aqueous solution of sodium ascorbate (15 mol %) and a 0.1 M aque-
ous solution of CuSO4 (10 mol %) was added. To this mixture,
2 equiv of the appropriate alkyne was added and the reaction mix-
ture was stirred at room temperature for 18–24 h. The reaction
mixture was diluted with EtOAc and extracted with H2O. The aque-
ous phase was extracted with EtOAc and the combined organic lay-
ers were dried over Na2SO4, filtered and concentrated under
reduced pressure. After purification by column chromatography
(CH2Cl2:MeOH 98.5:1.3), the desired triazoles 3a–j were obtained
in good yields.
1H NMR (300 MHz, CDCl3): d 7.53 (s, 1H, triazole H), 5.29 (t, 1H,
J = 9.2 Hz, H-3), 4.64–4.71 (m, 1H, H-1), 4.49 (dt, 1H, J = 6.7 Hz and
9.1 Hz, H-1), 2.91–3.12 (m, 2H, H-2), 2.72 (t, 2H, J = 7.6 Hz, H-4),
1.67 (quintet, 2H, J = 7.5 Hz, H-5), 1.20–1.40 (m, 14H, H-6, H-7,
H-8, H-9, H-10, H-11 and H-12), 0.87 (t, 3H, J = 6.7 Hz, H-13); 13C
NMR (75 MHz, CDCl3): d 171.3, 149.3, 120.8, 66.5, 57.6, 32.0,
29.74, 29.68, 29.51, 29.46, 29.45, 29.44, 29.41, 25.8, 22.8, 14.3;
ESI-MS for
294.2176 (Supplementary data).
C
16H27N3O2 [MÀH]+, Found, 294.2180; Calcd,
4.2.9. 3g: 3-(4-Dodecyl-1H-1,2,3-triazol-1yl)dihydrofuran-
2(3H)-one
4.2.3. 3a: 3-(4-Butyl-1H-1,2,3-triazol-1yl)dihydrofuran-2(3H)-
one
1H NMR (300 MHz, CDCl3): d 7.53 (s, 1H, triazole H), 5.29 (t, 1H,
J = 9.2 Hz, H-3), 4.64–4.71 (m, 1H, H-1), 4.49 (dt, 1H, J = 7.0 Hz and
9.0 Hz, H-1), 2.92–3.12 (m, 2H, H-2), 2.72 (t, 2H, J = 7.6 Hz, H-4),
1.67 (quintet, 2H, J = 7.4 Hz, H-5), 1.23–1.38 (m, 18H, H-6, H-7,
H-8, H-9, H-10, H-11, H-12, H-13 and H-14), 0.87 (t, 3H,
J = 6.7 Hz, H-15); 13C NMR (75 MHz, CDCl3): d 171.2, 149.3, 120.8,
66.5, 57.6, 32.1, 29.82, 29.80, 29.79, 29.7, 29.52, 29.50, 29.46,
29.45, 29.43, 25.8, 22.8, 14.3; ESI-MS for C18H31N3O2 [MÀH]+,
Found, 322.2495; Calcd, 322.2489 (Supplementary data).
1H NMR (300 MHz, CDCl3): d 7.53 (s, 1H, triazole H), 5.29 (t, 1H,
J = 9.3 Hz, H-3), 4.64–4.71 (m, 1H, H-1), 4.49 (dt, 1H, J = 6.9 Hz and
9.0 Hz, H-1), 2.92–3.12 (m, 2H, H-2), 2.74 (t, 2H, J = 7.7 Hz, H-4),
1.61–1.72 (m, 2H, H-5), 1.33–1.45 (m, 2H, H-6), 0.93 (t, 3H,
J = 7.4 Hz, H-7); 13C NMR (75 MHz, CDCl3): d 171.3, 149.3, 120.9,
66.6, 57.7, 31.6, 29.5, 25.6, 22.5, 14.0; ESI-MS for C10H15N3O2
[MÀH]+. Found, 210.1244; Calcd, 210.1237 (Supplementary data).
4.2.4. 3b: 3-(4-Pentyl-1H-1,2,3-triazol-1yl)dihydrofuran-2(3H)-
one
4.2.10. 3h: 3-(4-Phenyl-1H-1,2,3-triazol-1yl)dihydrofuran-
2(3H)-one
1H NMR (300 MHz, CDCl3): d 7.53 (s, 1H, triazole H), 5.30 (t, 1H,
J = 9.2 Hz, H-3), 4.63–4.71 (m, 1H, H-1), 4.49 (dt, 1H, J = 6.7 Hz and
9.1 Hz, H-1), 2.91–3.11 (m, 2H, H-2), 2.72 (t, 2H, J = 7.6 Hz, H-4),
1H NMR (300 MHz, CDCl3): d 8.05 (s, 1H, arom. H), 7.81–7.86 (m,
2H, arom. H), 7.30–7.46 (m, 3H, arom. H), 5.39 (t, 1H, J = 9.3 Hz,