¹H and ¹³C NMR Assignments of Cytotoxic 3S-1,2,3,4-Tetrahydro-β-carboline-3-carboxylic Acid from the Leaves of Cichorium endivia

Table 1

¹H and ¹³C NMR spectroscopic data for compound 1.

Number	𝛿H^ab	𝛿C^ac	𝛿H^de	𝛿H^d [4]	𝛿H^d [5]	𝛿C^d [5]
1a	4.38 d (15.6)	40.5 t	4.15 d  (15.3)	—	—	40.3
1b	4.54 d  (15.6)		4.23 d  (15.9)	4.22 d  (4.8)	—
3	4.27 dd  (10.4, 5.6)	55.0 d	3.60 m	3.14	—	55.3
4a	3.13 dd  (10.8, 16.4)	21.7 t	2.81 dd-like	2.83 ddd  (10.5, 5.0, 2.4)	—	18.0
4b	3.38 dd  (5.6, 16.4)		3.13 br d-like	3.69 dd  (10.5, 5.0)	—
4a′		104.9 s				104.3
4b′		125.6^f s				128.5
5	7.53 d  (8.0)	118.2 d	7.32 d  (7.5)	7.33 d  (8.0)	7.38 d  (8.2)	118.5
6	7.13 t  (7.6)	120.0 d	7.06 t  (7.5)	7.08 t  (8.0)	7.06 t  (8.2)	117.5
7	7.22 t  (8.0)	122.9 d	6.97 t  (7.8)	6.99 t  (7.5)	6.96 t  (8.2)	121.1
8	7.43 d  (8.0)	111.9 d	7.43 d  (7.5)	7.44 d  (7.5)	7.44 d  (8.2)	111.8
8a		136.7 s				136.1
9a		125.4^f s				—
COOH		171.3 s	10.91 s	10.93 s	—	165.6
9-NH				—	10.66 s

^aD₂O + drops of F₃CCOOD; ^b400 MHz. ^c100 MHz. ^din DMSO-d₆; ^e300 MHz. ^fAssignments may be interchanged.