Table 1 ¹H- and ¹³C-NMR data of 1,1′-biuracil (1) and uracil (2) (600 MHz, DMSO-d₆, δ_H; 150 MHz, DMSO-d₆, δ_C)

1, 1′

–

–

1

–

10.82, br. s

2, 2′

151.5

–

2

152.0

–

3, 3′

–

10.98, br. s

3

–

11.02, br. s

4, 4′

164.3

–

4

164.8

–

5, 5′

100.2

5.44, br. d, 7.2

5

100.7

5.45, ddd, 6.6, 1.8, 1.2

6, 6′

142.2

7.38, d, 7.2

6

142.7

7.40, dd, 6.6, 4.8