Synthesis and Validation of Cyanine-Based Dyes for DIGE - Difference Gel Electrophoresis (DIGE): Methods and Protocols - page 70

Fig. 1. Synthesis of the benzoxazolium Cy2 dye and its N -hydroxysuccinimide (NHS) ester.
1,462, 1,388, 1,188, 1,147, 1,025, 759/cm. 1 H NMR
(400 MHz, DMSO- d 6 ): d 8.09-8.23 (2H, m), 7.71-7.80 (2H,
m), 4.60 (2H, q, J =7.3 Hz), 3.02 (3H, s), 1.43 (2H, t,
J = 7.3 Hz). 13 C NMR (100 MHz, DMSO- d 6 ): d 169.03,
147.91, 129.73, 129.04, 128.13, 115.00, 113.42, 42.38,
13.84, 13.40.
B. N-((4-Carboxymethyl)phenylmethyl)-2-methylbenzoxazolium
bromide (4) . A mixture of 2-methylbenzoxazole (1) (Aldrich,
2.24 g, 0.01 mol) and 4-(bromomethyl)phenylacetic acid (3)
(Aldrich, 3.22 g, 0.01 mol) in 1,2-dichlorobenzene (Aldrich)
was heated at 110°C for 12 h. The solution was cooled to
room temperature, and the residue obtained was fi ltered and