It is notable that none of the aromatic peaks were overlapped by each other in contrast to the previously reported spectrum acquired in DMSO-d6. 9 Chemical shift of the C 16 and C 17 methyl groups on the pyrrole ring (at around 1.88 ppm and 1.86 ppm) were much lower than those from the spectrum acquired in DMSO-d6 so that they did not overlap with two H-C 27 doublets of malate at around 2.72 and 2.54 ppm as well. Due to the baseline affected by the water-suppression near 4.80 ppm, peak integration for H-C 26 was rather inaccurate (0.73H). H-C 23 quartet at 3. where the first three were split into doublet-of-doublets and a triplet-of-doublet, due to a combination of hydrogen-fluorine and hydrogen-hydrogen couplings across the ring. The J-coupling constants were estimated to be 3 J H-F = 8.92 Hz (ortho, H-C 4 ), 4 J H-H = 2.43 Hz (meta, H-C 4 ), 3 J H-F = 8.67 Hz (ortho, H-C 6 ), 4 J H-H = 2.17 Hz (meta, H-C 6 ), 3 J H-H = 8.23 Hz (ortho, H-C 6 ), 4 J H-F = 4.24 Hz (meta, H-C 7 ), and 3 J H-H = 7.90 Hz (ortho, H-C 7 ). 13 C carbon NMR was acquired in the same environment which gave good signal-to-noise ratios with respect to peaks for carbonyl carbons and aromatic carbons that do not possess any hydrogen ChemRxiv 2022 4 atom (Figure ). Carbon-fluorine coupling constants from the aromatic hydrogen peaks of the indolinone ring, were estimated to be 1 J C-F = 235.62 Hz (ipso, C 5 ), 2 J C-F = 24.78 Hz (ortho, C 4 ), 2 J C-F = 24.19 Hz (ortho, C 6 ), 3 J C-F = 8.57 Hz (meta, C 7 ), and 3 J C-F = 9.01 Hz (meta, C 9 ), where no para coupling was observed (Figure ). It is uncertain that singlets of ipso carbon doublet have particularly asymmetric peak intensities throughout repeated experiments, where that of 13 C spectrum acquired in DMSO-d6 showed similar singlet peak intensities within the corresponding doublet. In-house measurement of the coupling constants in DMSO-d6 at 100 MHz resulted in 1 J C- F = 234.33 Hz (ipso, C 5 ), 2 J C-F = 25.52 Hz (ortho, C 4 ), 2 J C-F = 24.21 Hz (ortho, C 6 ), 3 J C-F = 8.52 Hz (meta, C 7 ), 3 J C-F = 9.53 Hz (meta, C 9 ), and 4 J C-F = 3.09 Hz (para, C 8 ) (Figure ). where key multi-bond couplings across the indolinone ring are exhibited. However, 13 C peak