As assigned(9 ) 4 eq 1 eq 0.1 M 16 h reality the 3 (59

As assigned(9 ) 4 eq 1 eq 0.1 M 16 h reality the 3 (59 ) eight (25 ) 9(7 ) four on r.t. 16 h Me2NCSCl (four eq) based eq the 1 eq that 0.1 MH-3 signal is downshifted from four.42 ppm to five.51 (five.49) ppm three carbamoylation at 3-OH was further 5 (73 ) four (23 ) four eq 1 eq 0.1 M 50 Me2NCOCl (four eq) relative to 5,7,20-O-trimethylsilybin (3) 16 h The (0 ) [21]. three the six H 5.51 (five.49) (H-3) for the 7 (19 ) 4 eq 0.1 M 50 16 h Et2NCOCl (four eq) confirmed by 1 eq vital HMBC correlations from (29 )signal at (46 ) the three (40 ) eight (42 ) 9 (14 ) four at 1 eq 0.1 M 50 16 h Me2NCSCl (four eq) signaleq 155.28 (carbonyl carbon from the dimethylcarbamoyl group, Figure 2). It really is C 3 (0 ) 5 (58 ) 4 (38 ) six eq three eq 0.two M 50 16 h Me2NCOCl (six eq) worth noting that the starting material Fmoc-Gly-Gly-OH site silibinin (1) (purchased from Fisher Scientific) was a 3 (0 ) six (69 ) 7 (24 ) six eq three eq 0.two M 50 16 h Et2NCOC (6 eq) three (7 ) eight (58 ) 9 (25 ) six equimolar diastereoisomeric mixture of silybin A and silybin B. The carbamoyled 3 eq 0.two M 50 16 h Me2NCSCl (6 eq) nearlyeq derivatives of 5,7,20-O-trimethylsilybin are hence diastereoisomeric mixtures at the same time, and a Isolated yields.(Thio)carbamoyl ChlorideMolecules 2021, 26,five ofsome NMR signals of these derivatives for that reason appear as a pair (see Table 2 and Components and Strategies).Table two. NMR information for five (1 H NMR: 300 MHz; 13 C NMR: 75 MHz). Position five (CDCl3 ) C , Type H , (J in Hz) HMBC (HC)two 80.96 (80.89), CH five.29 (5.27) d (11.eight) C-4, C-13, C-14, C-15 3 74.67 (74.52), CH five.51 (five.49) d (11.eight) C-4, C-14, 3-OC(O)N4 186.40, C 4a 104.24, C five 164.18, C 6 93.47, CH six.09.06, overlapped C-4a, C-7, C-8 7 166.43, C eight 93.38, CH 6.09.06, overlapped C-6, C-7, C-8a 8a 162.39, C 10 78.36, CH four.02, ddd (eight.1, 5.4, 3.9) C-11 Molecules 2021, 26, x FOR PEER Overview 11 76.28 (76.20), CH four.95 (four.93), d (eight.1) C-17, C-18, C-225 of 17 12a 144.03 (144.00), C 13 116.47, CH 7.13, d (two.4) C-12a, C-14, C-15 14 129.56 (129.43), C two.two. Structure 120.95 (120.78), of 3-O-Carbamoyl-5,7,20-O-trimethylsilybin 5 C-14, C-15a Determination 15 CH 7.00.91, overlapped 16 117.11 of five,7,20-O-trimethyl-3-O-(N,N-dimethylcarbamoyl)-silybin (five) was CH 7.00.91, overlapped C-14, C-16a The structure (117.02), 16a 144.03 (144.00), C elucidated by interpreting its 1D- and 2D-NMR information (Table two), too as higher resolution 17 128.55 (128.52), C MS and IR data. The structure ofCH five was characterized by the existence of one signal at 2.85 18 110.13 (109.99), 7.00.91, overlapped C-11, C-19, C-22 Molecules 2021, 26, x FOR PEER Critique six of at ppm representing six protons in its 1H NMR spectrum (Supplementary Components) and17 19 149.64, C 13C NMR spectrum for an added dimethylcarbamoyl 20 36.75 (36.08) 149.41 (149.35), its C and 155.28 in 21 CH six.87, (8.1) C-17, (three), group when 111.24 (111.18), compared together with the beginning materiald5,7,20-O-trimethylsilybinC-20 which 120.19, CH 7.00.91, overlapped C-17, was 22 corroborated by the HRMS information. The dimethylcarbamoyl group in 5 wasC-18 22 120.19, CH 7.00.91, overlapped C-17, C-18assigned to 3.87.75, overlapped 3.87.75, overlapped 23 61.64, C-11 3-OH 3-Chloro-5-hydroxybenzoic acid medchemexpress determined by the fact that theCH2 signal is downshifted from four.42 ppm to 5.51 (five.49) C-11 23 61.64, CH2H-3 3.51, dd (12.six, three.51, dd (12.six, three.9) three.9)ppm relative to 5,7,20-O-trimethylsilybin (3) [21]. The carbamoylation at 3-OH was fur155.28, C ther confirmed by the crucial HMBC correlations from the signal at H 5.51 (five.49) (H-3) to 155.28, C the signal at C 155.28 (carbonylCH3 carbon in the two.85, s dimethylcarbamoyl group, Fig.