Compound

Tautomeric composition in DМSОd₆, %, (48 h after dissolution)

lgK_T^*

E,E'-А

E,Z'-А

B

2a

?

0.5

99.5

2.299

2b

?

2

98

1.690

2c

?

4

96

1.380

2d

?

7

93

1.123

2e

?

10

90

0.954

2f

1

10

89

0.908

2g

6

38

56

0.105

2h

12

61

27

?0.432