Ultrasonic-Assisted Synthesis of Two t-Butoxycarbonylamino Cephalosporin Intermediates on SiO₂

Table 3

Comparison of ¹H NMR data (4a).

Lee et al. reported (500 MHz, CDCl3)	Synthetic 4a (300 MHz, DMSO-d6)
1.45 (s, 9H)	1.37 (s, 9H)
3.47 (d, 1H, J = 18.2 Hz),	3.48 (d, 1H, = 17.91 Hz)
3.66 (d, 1H, J = 18.2 Hz)	3.64 (d, 1H, = 9.65 Hz)
	3.73 (s, 3H)
4.55 (d, 1H, J = 12.1 Hz)	4.41 (d, 1H, = 11.31 Hz)
	4.49 (d, 1H, = 11.07 Hz)
4.95 (d, 1H, J = 4.6 Hz)	5.07 (d, 1H, = 3.93 Hz)
5.23 (s, 2H)	5.12 (d, 1H, = 12.09 Hz)
5.61 (dd, 1H, J = 5.0, 9.5 Hz)	5.19 (d, 1H, = 11.73 Hz)
	5.48 (s, 2H)
6.88–6.91 (, 2H)	6.89–6.92 (, 2H)
7.33–7.36 (, 2H)	7.32–7.34 (, 2H)

Data taken from [4]; this work.