TABLE 4.
1H and 13C NMR chemical shifts (in ppm) and proton coupling constants (Hz, in parentheses) of the novel MAA N-(4,5-dihydroxy-5-(hydroxymethyl)-2-methoxy-3-oxocyclohex-1-en1-yl)-N-methylserine (klebsormidinB) isolated from the terrestrial green alga Klebsormidiumcrenulatum.
| N | 13C | 1H | COSY | HMBC |
| 1 | 192.3 | – | ||
| 2 | 132.7 | – | ||
| 3 | 159.2 | – | ||
| 4 | 37.9 | a) 2.99, d (17.6), | 4b | 3,2,6,5 |
| b) 2.88, d (17.6) | 4a | 3,12 | ||
| 5 | 76.5 | – | ||
| 6 | 74.7 | 4.29, s | 1 | |
| 7 | 68.1 | a) 3.62, d (11.7), | 7b | 4,5,6 |
| b) 3.55, d (11.7) | 7a | 4,5,6 | ||
| 8 | 63.0 | 3.51, s | 2 | |
| 9 | 174.6 | – | ||
| 10 | 66.8 | 3.68, ov | 11b | 9,11 |
| 11 | 61.5 | a) 4.02, dd (12.5, 3.6) | 10, 11b | 9 |
| b) 3.99, dd (12.5, 5.0) | 10, 11a | 9 | ||
| 12 | 34.2 | 2.76, s | 10 |