Table 1 Chemical shifts for enolic H-atom and carbonyl carbon atom in cis keto-enol form of compounds 2, 3 and 4 in CDCl 3 solution
Comp. | δ(OH) | δ(CO) | Comp. | δ(OH) | δ(CO) | Comp. | δ(OH) | δ(CO) |
|---|---|---|---|---|---|---|---|---|
2a | 15.91 | 183.6 | 3a | 16.41 | 180.5 | 4a | 16.86 | 181.3 |
2b | 16.19 | 183.8 | 3b | 16.78 | 180.6 | 4b | 17.21 | 181.5 |
2c | 15.96 | 183.6 | 3c | 16.52 | 180.5 | 4c | 16.96 | 181.4 |
2d | 16.23 | 184.7 | 3d | 16.77 | 181.6 | 4d | 17.19 | 182.4 |
2e | 16.02 | 183.2 | 3e | 16.62 | 180.1 | 4e | 17.05 | 181.0 |
2f | 15.83 | 183.2 | 3f | 16.34 | 180.1 | 4f | 16.74 | 181.0 |