5) Answer the following questions. a) DBE b) What signal(s) in the 13C NMR spectrum are useful to help determine the structure? Why? c) What signal(s) in the HSQC spectrum are useful to help determine the structure? Why? d) What signal(s) in the HMBC spectrum are useful to help determine the structure? Why? 8888 0 0 0 0687 - 2.858 -2.615 -- 2.582 1 1H NMR, C24H23 NO2 500 MHz, CDCl3 6.74 6.70 6.68 6.72 ppm 6.00 2.95 2.90 6.58 6.57 6.56 6.55 ppm 6.05 ppm 2.85 2.80 2.75 ppm 2.70 2.65 2.60 2.55 6 2.236 2.210 - 2.208 3.33 2.12 2.56 2.54 2.52 ppm 1.23 2.24 2.23 2.22 2.21 2.20 2.19 ppm 2.02 2.00 1.98 ppm 1.25 ppm 1.00 1.11 1.23 D E FG HT 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.0 3.5 3.0 2.5 2.0 1.5 4.5 ppm 1.0 202.35 197.66 13C NMR, C24H23 NO2 125 MHz, CDCI: 10/13 5 7 1376 17 18 9h4 19 3 80 210 200 190 180 170 160 150 140 130 120 110 90 70 60 50 40 30 20 10 0 -10 100 ppm IT" 7.5 CDCI COSY C24H23 NO2 6.0 -> i 50 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.0 3.5 3.0 2.5 2.0 1.5 1.0 4.5 ppm 19 HSQC C24H23 NO2 20 18 CDCI: - 30 17 40 16 15 -50 60 -70 - 80 90 100 110 - 120 14 29-13 - 130 140 - 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 Mihin BC D E F G H 1 F1 (ppm) 19 HMBC 18 C24H23 NO2 CDCI 17 116 (15 DE 10-13 3 D T T 8 7 6 5 4 3 2 F2 (ppm)