Please do not adjust margins
Organic & Biomolecular Chemistry
Page 7 of 9
DOI: 10.1039/C7OB02188G
Journal Name
ARTICLE
APEX‐IV Fourier transform mass spectrometer. Mass M2‐33/67, δ 178.7, 173.9, 173.4, 167.5, 150.5, 141.3, 126.8,
spectroscopy (MS) of the hydrolysis products was performed 115.7, 71.0, 69.6, 69.5, 69.4, 69.0, 68.6, 58.0, 39.0, 38.7, 20.7,
on a quadrupole rods SQ Detector 2 mass spectrometer 19.9. ESI‐MS
(
M2‐94/6): calcd for C14H24NO7 [M‐H]‐
(Waters Corporation) in positive and negative ion modes, 318.153798; found 318.155826. ESI‐MS (M2‐33/67): calcd for
respectively.
C14H24NO7 [M‐H]‐ 318.155826.; found 318.154729.
Synthesis and isomerization of n‐butyl citraconamic acids
2,3‐Dimethyl maleamic acid (M3)
n‐Butyl amine (1.0 mmol) and citraconic anhydride (1.0
2,3‐Dimethylmaleic anhydride (1.0 mmol), OEG4‐NH2 (1.0
mmol) were added in anhydrous dichloromethane (DCM, 2.0 mmol), and TEA (2.2 equiv.) were added in anhydrous DMF
o
1
mL). The reaction mixture was stirred at 0 C. H NMR was (2.0 mL) at 0 oC. After stirring for 1 h, 1 M NaHCO3 solution (1.2
recorded at specific time point. The ratio of the α‐CH3 isomer equiv.) was added to the mixture. The mixture was
1
and the β‐CH3 isomer was estimated by the H NMR spectra. concentrated on a rotary evaporator. M3 was obtained as a
o
o
o
1
By changing the temperature from 0 C to 15 C or 30 C, the white solid (yield > 99 %). H NMR (400 MHz, D2O, ppm): δ
samples with different ratios of the two isomers could be 3.70‐3.65 (m, 10H), 3.64‐3.56 (m, 4H), 3.38 (t, J = 5.2 Hz, 2H),
obtained. Also, the isomerization experiments at different 3.36 (s, 3H),1.83 (s, 3H), 1.80 (s, 6H). 13C NMR (101 MHz, D2O,
temperatures were carried out following the same procedure.
ppm): δ178.3, 174.3, 164.9, 137.8, 127.9, 70.9, 69.6, 69.5,
69.5, 69.4, 68.6, 58.0, 39.0, 36.9, 31.3, 15.5, 14.5. ESI‐MS: calcd
for C15H26NO7 [M‐H]‐ 332.170333; found 332.170379.
Optimization of the synthetic condition of n‐butyl‐2.3‐
dimethylmaleamic acid
Hydrolysis kinetics measured by 1H NMR
n‐Butyl amine (1.0 mmol) and 2,3‐dimethylmaleic anhydride
(1.0 mmol) were added in anhydrous tetrahydrofuran (THF, 2.0
Each maleamic acid derivative (1 mg, sodium salt) was
dissolved in 500 μL of PB (50 mM, pH 5.5 or 6.5 or 7.4) in a
NMR tube. The NMR tubes were incubated at 37 oC, and the 1H
NMR spectrum was recorded at specific time point.
o
mL). The reaction mixture was stirred at 30 C for 4 h. After
removing THF, the residue was measured by 1H NMR to
determine the amount of various compounds in the mixture.
Similar procedure was used for other experimental conditions,
but the solvent was not removed when using DMF as the
solvent.
Acknowledgements
This work was financially supported by the National Key
Research and Development Program of China (No.
2016YFA0201400) and National Natural Science Foundation of
China (No. 21534001).
Syntheses of M1‐M3
Phthalamic acid (M1)
Phthalic anhydride (1.0 mmol) and mOEG4‐NH2 (1.0 mmol)
were added in anhydrous DCM (2.0 mL) at ambient
temperature. After stirring for
1 h, the mixture was
Notes and references
1. D. Ling, W. Park, S. J. Park, Y. Lu, K. S. Kim, M. J. Hackett, B.
H. Kim, H. Yim, Y. S. Jeon, K. Na and T. Hyeon, J. Am. Chem.
Soc., 2014, 136, 5647‐5655.
2. R. Xu, G. Zhang, J. Mai, X. Deng, V. Segura‐Ibarra, S. Wu, J.
Shen, H. Liu, Z. Hu, L. Chen, Y. Huang, E. Koay, Y. Huang, J. Liu,
J. E. Ensor, E. Blanco, X. Liu, M. Ferrari and H. Shen, Nat.
Biotechnol., 2016, 34, 414‐418.
3. W. Sun, T. Jiang, Y. Lu, M. Reiff, R. Mo and Z. Gu, J. Am.
Chem. Soc., 2014, 136, 14722‐14725.
concentrated on a rotary evaporator. The concentrated
product was added into a 1 N NaHCO3 solution (1.2 equiv.) and
lyophilized. M1 was obtained as a white solid (yield: >99 %). 1H
NMR (400 MHz, D2O, ppm): δ 7.57 (dd, J = 7.4, 1.5 Hz, 1H),
7.52‐7.40 (m, 3H), 3.71‐3.51 (m, 16H), 3.29 (s, 3H). 13C NMR
(101 MHz, D2O, ppm): δ 75.8, 173.0, 164.2, 137.5, 134.3,
130.3, 129.4, 128.0, 127.1, 70.9, 69.5, 69.5, 69.4, 69.4, 69.3,
68.7, 58.0, 39.4. ESI‐MS: calcd for C17H24NO7 [M‐H]‐
354.154189; found 354.154729.
Citraconamic acids (M2‐α/β)
Synthesis of M2‐α/β followed the same procedure as for
M1, except that the reaction temperature and time were
4. Y. Zhang, Q. Yin, L. Yin, L. Ma, L. Tang and J. Cheng, Angew.
Chem., Int. Ed. , 2013, 52, 6435‐6439.
o
o
changed to 30 C, 24 h (for M2‐94/6) or 0 C, 1 h (for M2‐
33/67). M2‐94/6 and M2‐37/6 were obtained as white solids
5. N. Fomina, C. McFearin, M. Sermsakdi, O. Edigin and A.
Almutairi, J. Am. Chem. Soc., 2010, 132, 9540‐9542.
6. X. Liu, J. Xiang, D. Zhu, L. Jiang, Z. Zhou, J. Tang, X. Liu, Y.
Huang and Y. Shen, Adv. Mater., 2016, 28, 1743‐1752.
7. Y. Ma, Y. Li, H. P. Xu, Z. Q. Wang and X. Zhang, J. Am. Chem.
Soc., 2010, 132, 442–443.
8. F. H. Meng, W. E. Hennink and Z. Y. Zhong, Biomaterials,
2009, 30, 2180‐2198.
9. B. P. Timko, M. Arruebo, S. A. Shankarappa, J. B. McAlvin,
O. S. Okonkwo, B. Mizrahi, C. F. Stefanescu, L. Gomez, J. Zhu,
1
after lyophilization (yield > 99 %). H NMR (400 MHz, D2O,
ppm): for M2‐94/6, δ 5.88 (M2‐β, q, J = 1.6 Hz, 0.06H), 5.59
(M2‐α, q, J = 1.6 Hz, 0.94H), 3.75‐3.61 (m, 14H), 3.47–3.37 (m,
5H), 1.99 (M2‐β, d, J = 1.6 Hz, 2.82H), 1.95 (M2‐α, d, J = 1.6 Hz,
0.18H); for M2‐33/67, δ 5.88 (M2‐β, q, J = 1.6 Hz, 0.67H), 5.59
(M2‐α, q, J = 1.6 Hz, 0.33H), 3.75–3.61 (m, 14H), 3.47–3.37 (m,
5H), 1.99 (M2‐α, d, J = 1.6 Hz, 0.99H), 1.95 (M2‐β, d, J = 1.6 Hz,
2.01H). 13C NMR (101 MHz, D2O): for M2‐94/6, δ 178.7, 167.5,
150.5, 115.7, 71.0, 69.6, 69.5, 69.4, 69.0, 58.0, 38.7, 20.7; for
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1‐3 | 7
Please do not adjust margins