LETTER
Synthesis of a Biotin-Labeled Quorum-Sensing Molecule
2125
(10) Analogues of the related signaling molecule N-3-
In summary, we report the efficient synthesis of the quo-
rum-sensing molecule OHHL (2) and the biotin-tagged
analogue 1. The binding properties of 1 with CarR are cur-
rently being investigated. Results from these investiga-
tions and the proof-of-principle target identification
experiments will be published in due course.
(oxododecanoyl)-L-homoserine lactone (OdDHL), used in
Pseudomonas aeruginosa, have been synthesized by
coupling using the acid, Meldrum’s acid, and the amine in
one pot: Chhabra, S. R.; Harty, C.; Hooi, D. S. W.; Daykin,
M.; Williams, P.; Telford, G.; Pritchard, D. I.; Bycroft, B. W.
J. Med. Chem. 2003, 46, 97; in our hands this method proved
less fruitful than the stepwise method employed therein.
(11) N-(3-Oxohexanoyl)-L-homoserine lactone(2): Rf = 0.23
(SiO2; EtOAc–PE, 8:2). IR (neat): nmax = 3301 (w, br), 2965
(w), 2878 (w), 1774 (s), 1716 (m), 1649 (s), 1535 (m), 1379
(m), 1221 (m), 1169 (s), 1021 (m) cm–1. 1H NMR (400 MHz,
CDCl3): d = 7.73 (1 H, br s, CONH), 4.63–4.51 [1 H, br m,
C(2)H], 4.43 [1 H, br t, J = 9.1 Hz, C(4)HaHb], 4.27–4.18 [1
H, br m, C(4)HaHb], 3.42 (2 H, s, COCH2CO), 2.68–2.58 [1
H, br m, C(3)HaHb], 2.47 (2 H, t, J = 7.3 Hz, CH3CH2CH2),
2.30–2.16 [1 H, br m, C(3)HaHb], 1.54 (2 H, sext, J = 7.3 Hz,
CH3CH2CH2), 0.86 (2 H, t, J = 7.5, CH3CH2CH2). 13C NMR
(100 MHz, CDCl3): d = 206.1 (C), 175.2 (C), 166.9 (C), 65.9
(CH2), 48.9 (CH), 48.7 (CH2), 45.4 (CH2), 29.2 (CH2), 16.8
(CH2), 13.4 (CH3). HRMS: m/z calcd for C10H15NO4Na+:
236.0899; found [ESI – Na+]: 236.0892; Dppm = –1.5; mp
Acknowledgment
This work was supported by grants from the EPSRC, BBSRC,
MRC, and Augustus and Harry Newman Foundation. We also ack-
nowledge the EPSRC National Mass Spectrometry Service Centre,
Swansea, for providing mass spectrometric data.
References and Notes
(1) For reviews on chemical genetics, see: (a) MacBeath, G.
Genome Biol. 2001, 2, 2005.1. (b) Spring, D. R. Chem. Soc.
Rev. 2005, 34, 472. (c) Walsh, D. P.; Chang, Y.-T. Chem.
Rev. 2006, 106, 2476.
(2) The complementary approach, reverse chemical genetics,
involves modulating a known protein and analyzing the
resulting phenotype.1b
25
80–81 °C (EtOAc–PE). [a]D +7.36 (c 0.95, CHCl3).
(12) Blackwell, H. E.; Geske, G. D.; Wezeman, R. J. WO 2006/
084056 A2, 2006.
(13) Compound 2: [a]D25 +7.36 (c 0.95, CHCl3). Sigma OHHL
[a]D25 +8.5 (c 0.12, CHCl3). These specific rotation values
are slightly lower than those reported by Blackwell and co-
workers,12a that is, [a]D25 +12.2 (c 2.7, CHCl3). Although
some racemization may have occurred during the synthesis
reported here, this did not affect binding of CarR. In our
hands coupling with HOBt was less successful.
(14) Polymer-bound DMAP was required in the final EDC-
mediated coupling to aid purification. The reaction products
and DMAP had very similar Rf values.
(3) For reviews on DOS, see: (a) Spandl, R. J.; Thomas, G. L.;
Diaz-Gavilan, M.; O’Connell, K. M. G.; Spring, D. R. Chem.
Rec. 2008, 129. (b) Nielsen, T. E.; Schreiber, S. L. Angew.
Chem. Int. Ed. 2008, 47, 48. (c) Spandl, R. J.; Spring, D. R.;
Bender, A. Org. Biomol. Chem. 2008, 6, 1149. (d) Tan, D.
S. Nat. Chem. Biol. 2005, 1, 74. (e) Thomas, G. L.; Wyatt,
E. E.; Spring, D. R. Curr. Opin. Drug Discovery Dev. 2006,
9, 700.
(4) For reviews and approaches to solving the target
identification problem, see: (a) Ahn, Y. H.; Chang, Y. T.
Acc. Chem. Res. 2007, 40, 1025. (b) Wong, C. C.; Cheng,
K. W.; He, Q. Y.; Chen, F. Proteomics: Clin. Appl. 2008, 2,
338. (c) Zheng, X. F. S.; Chan, T. F.; Zhou, H. H. Chem.
Biol. 2004, 11, 609.
(5) Burdine, L.; Kodadek, T. Chem. Biol. 2004, 11, 593.
(6) For reviews of quorum sensing involving N-acylated
homoserine lactones, see: (a) Hodgkinson, J. T.; Welch, M.;
Spring, D. R. ACS Chem. Biol. 2007, 2, 715. (b) Geske, G.
D.; Oneill, J. C.; Miller, D. M.; Wezeman, R. J.; Mattmann,
M. E.; Lin, Q.; Blackwell, H. E. ChemBioChem 2008, 9,
389.
(7) For selected recent examples, see: (a) Thomas, G. L.;
Bohner, C. M.; Williams, H. E.; Walsh, C. M.; Ladlow, M.;
Welch, M.; Bryant, C. E.; Spring, D. R. Mol. BioSyst. 2006,
2, 132. (b) Welch, M.; Mikkelsen, H.; Swatton, J. E.; Smith,
D.; Thomas, G. L.; Glansdorp, F. G.; Spring, D. R. Mol.
BioSyst. 2005, 1, 196. (c) Welch, M.; Dutton, J. M.;
Glansdorp, F. G.; Thomas, G. L.; Smith, D. S.; Coulthurst,
S. J.; Barnard, A. M. L.; Salmond, G. P. C.; Spring, D. R.
Bioorg. Med. Chem. Lett. 2005, 15, 4235. (d) Glansdorp, F.
G.; Thomas, G. L.; Lee, J. J. K.; Dutton, J. M.; Salmond, G.
P. C.; Welch, M.; Spring, D. R. Org. Biomol. Chem. 2004, 2,
3329.
Synthesis of 18
A round-bottom flask, equipped with a magnetic stirrer,
containing the ester 17 (529 mg, 1.02 mmol), LiOH·H2O (98
mg, 2.33 mmol) and 66% aq MeOH (25 mL) was stirred at
r.t. for 16 h. The solvent was removed in vacuo to give the
lithium salt of the corresponding acid (structure not shown)
as a white solid (550 mg). The salt was used in subsequent
reactions without further purification. A round-bottom flask,
equipped with a magnetic stirrer, containing the lithium salt
(0.55 g, 1.09 mmol), EDC (0.27 g, 1.42 mmol), polymer-
bound DMAP (5 mmol/g, 1.1 g, 5.46 mmol), and DMF (40
mL) was stirred at r.t. for 15 min before being charged with
L-homoserine lactone hydrobromide (1.02 g, 5.6 mmol) and
stirred at r.t. for 16 h. The crude reaction mixture was filtered
and solvent removed in vacuo. The crude product was
purified by column chromatography to give 18 as a colorless
oil (0.43 g, 68% over 2 steps).
Rf = 0.36 (SiO2; CH2Cl2–MeOH, 85:15). IR (neat): nmax
=
3391 (s, br), 2932 (w, br), 1766 (m), 1645 (s) br, 1549 (s),
1474 (m), 1355 (m), 1063 (s) cm–1. 1H NMR (400 MHz,
CD3OD): d = 4.69–4.52 [2 H, m, NHCHCH2S and C(2)H],
4.48 [1 H, t, J = 9.2 Hz, C(4)HaHb], 4.41–4.29 [2 H, m,
NHCHCH2S and C(4)HaHb], 4.13–3.94 [4 H, m,
(8) A solution-phase route to OHHL(2): Dekhane, M.; Douglas,
K. T.; Gilbert, P. Tetrahedron Lett. 1996, 37, 1883.
(9) The synthesis of native N-acylated homoserine lactones
[including OHHL(2)] and non-natural analogues on solid
support: (a) Geske, G. D.; O’Neill, J. C.; Blackwell, H. E.
ACS Chem. Biol. 2007, 2, 426. (b) Geske, G. D.; O’Neill,
J. C.; Miller, D. M.; Mattmann, M. E.; Blackwell, H. E.
J. Am. Chem. Soc. 2007, 129, 13613. (c) Geske, G. D.;
Wezeman, R. J.; Siegel, A. P.; Blackwell, H. E. J. Am. Chem.
Soc. 2005, 127, 12762.
C(OCH2CH2O)CH2], 3.67–3.54 (6 H, m, OCH2CH2O and
NHCH2CH2O), 3.54 (2 H, t, J = 6.1 Hz, OCH2CH2CH2C),
3.35–3.47 (2 H, br m, NHCH2CH2O), 3.30–3.22 (1 H, m,
SCH), 2.97 (1 H, dd, J = 12.7, 5.1 Hz, SCHaHb), 2.75 (1 H,
d, J = 12.7 Hz, SCHaHb), 2.66–2.49 [3 H, m,
C(OCH2CH2O)CH2CO and C(3)HaHb)], 2.43–2.30 [1 H, m,
C(3)HaHb], 2.26 (2 H, t, J = 7.1 Hz,
CH2CH2CH2CH2CONH], 1.88–1.55 (8 H,
CH2CH2CH2CH2CONH and OCH2CH2CH2C), 1.53–1.41 (2
Synlett 2008, No. 14, 2122–2126 © Thieme Stuttgart · New York