Synthesis and Bioactivity of Dimethyl (2,3- Dihydrobenzo B 1,4 Dioxin-6-Yl) (Aryl Amino)Methyl

S 1

Synthesis and Bioactivity of Dimethyl (2,3- dihydrobenzo [b][1,4] dioxin-6-yl) (aryl amino)methyl phosphonates

Ch. SyamaSundar, N. Bakthavatchala Reddy, S. Siva Prasad, K. Uma MaheswaraRao, S. H. Jaya Prakash, and C. Suresh Reddy*

Department of Chemistry, Sri Venkateswara University, Tirupati, Andhra Pradesh, India.

E-mail:

Supplemental Materials

Characterization Data for Products

Spectral data for the title compounds (4a-o):

Dimethyl (2,3-dihydrobenzo[b][1,4]dioxin-6-yl)(phenylamino) methylphosphonate (4a):

Brown Solid, Yield: 94 %, Mp: 184-186 °C. IR (KBr) (νmax, cm-1): 3296 (NH), 1235 (P=O), 751 (P-Caliphatic). 1H NMR (400 MHz, CDCl3) δ: 3.53 (3H, d, J = 12 Hz, P-OCH3), 3.77 (3H, d, J = 8 Hz, P-OCH3), 4.21 (4H, s, OCH2CH2O), 4.68 (1H, d, J = 20 Hz, P-CH), 4.73 (1H, s, NH), 6.58-7.13 (8H, m, Ar-H). 13C NMR (100.5 MHz, CDCl3) δ: 53.8 (d, J = 12 Hz, 2 X P-OCH3), 54.9 (d, J = 152 Hz, P-CH), 64.2 (C-4 & C-5), 113.8 (C-21 & C-61), 116.6 (C-6), 117.5 (C-3), 118.5 (C-2), 120.7 (C-41), 128.5 (C-1), 129.1 (C-31 & C-51), 143.3 (C-7), 143.7 (C-8), 146.0 (C-11). 31P NMR (161.7 MHz, DMSO-d6) δ: 20.0. EI-MS (m/z, %): 350 (M+1, 20), 349 (M+•, 100). Anal.Calcd for C17H20NO5P: C, 58.45; H, 5.77; N, 4.01; Found: C, 58.35; H, 5.67; N, 3.95.

Dimethyl (2,3-dihydrobenzo[b][1,4]dioxin-6-yl)(4-fluorophenylamino) methyl phosphonate (4b):

Red Solid, Yield: 90 %, Mp: 171-173 °C. IR (KBr) (νmax, cm-1): 3298 (NH), 1246 (P=O), 749 (P-Caliphatic). 1H NMR (400 MHz, DMSO-d6) δ: 3.48 (3H, d, J = 12 Hz, P-OCH3), 3.66 (3H, d, J = 12 Hz, P-OCH3), 4.19 (4H, s, OCH2CH2O), 4.95 (1H, dd, J = 12 Hz, J = 28 Hz, P-CH), 6.23-6.26 (1H, m, NH), 6.76-7.02 (7H, m, Ar-H). 13C NMR (100.5 MHz, DMSO-d6) δ: 52.9 (d, J = 7 Hz, P-OCH3), 53.3 (d, J = 6 Hz, P-OCH3), 52.9 (d, J = 153 Hz, P-CH), 63.9 (C-4 & C-5), 114.4 (C-31 & C-51), 114.8 (C-6), 115.0 (C-21 & C-61), 116.8 (C-3), 121.2 (C-2), 129.3 (C-1), 142.7 (C-7), 142.9 (C-8), 143.6 (C-11), 154.8 (C-F, d, J = 203 Hz, ). 31P NMR (161.7 MHz, DMSO-d6) δ: 22.2. EI-MS (m/z, %): 368 (M+1, 18), 367 (M+•, 100). Anal.Calcd for C17H19FNO5P: C, 55.59; H, 5.21; N, 3.81. Found: C, 55.49; H, 5.16; N, 3.75.

Dimethyl (4-chlorophenylamino)(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)methyl phosphonate (4c):

Brown Solid, Yield: 89 %, Mp: 175-176 °C. IR (KBr) (νmax, cm-1): 3286 (NH), 1222 (P=O), 758 (P-Caliphatic). 1H NMR (400 MHz, DMSO-d6) δ: 3.55 (3H, d, J = 10.2 Hz, P-OCH3), 3.75 (3H, d, J = 10 Hz, P-OCH3), 4.22 (4H, s, OCH2CH2O), 4.67 (1H, d, J = 24.4, P-CH), 6.54 (1H, s, NH), 6.74-7.32 (7H, m, Ar-H). 13C NMR (100.5 MHz, DMSO-d6) δ: 52.8 (d, J = 7.2 Hz, P-OCH3), 53.3 (d, J = 7.1 Hz, P-OCH3), 55.2 (d, J = 152.4 Hz, P-CH), 64.8 (C-4 & C-5), 112.8 (C-6), 114.3 (C-3), 115.4 (C-21 & C-61), 120.7 (C-2), 128.1 (C-41), 128.8 (C-31 & C-51), 129.9 (C-1), 140.0 (C-11) 143.2 (C-8), 143.9 (C-7). 31P NMR (161.7 MHz, DMSO-d6) δ: 21.1. EI-MS (m/z, %): 385 (M+2, 32), 383 (M+•, 100). Anal.Calcd for C17H19ClNO5P: C, 53.21; H, 4.99; N, 3.65; Found: C, 53.14; H, 4.90; N, 3.60.

Dimethyl (2,3-dihydrobenzo[b][1,4]dioxin-6-yl)(4-methoxyphenylamino) methylphosphonate (4d):

Yellow Solid, Yield: 96 %, Mp: 142-144 °C. IR (KBr) (νmax, cm-1): 3280 (NH), 1239 (P=O), 759 (P-Caliphatic). 1H NMR (400 MHz, DMSO-d6) δ: 3.39 (3H, d, J = 10.8 Hz, P-OCH3), 3.52 (3H, d, J = 10.6 Hz, P-OCH3), 3.85 (3H, s, OCH3), 4.30 (4H, s, OCH2CH2O), 4.54 (1H, d, J = 24.8, P-CH), 6.52 (1H, s, NH), 6.78-7.39 (7H, m, Ar-H). 13C NMR (100.5 MHz, DMSO-d6) δ: 53.2 (d, J = 6.8 Hz, P-OCH3), 53.9 (d, J = 6.4 Hz, P-OCH3), 54.8 (d, J = 154.8 Hz, P-CH), 56.2 (Ar-OCH3), 64.2 (C-4 & C-5), 112.8 (C-6), 114.8 (C-3), 115.5 (C-31 & C-51), 115.9 (C-21 & C-61), 122.8 (C-2), 130.4 (C-1), 138.6 (C-11), 143.5 (C-8), 144.2 (C-7), 151.4 (C-41). 31P NMR (161.7 MHz, DMSO-d6) δ: 21.8. EI-MS (m/z, %): 380 (M+1, 22), 379 (M+•, 100). Anal.Calcd for C18H22NO6P: C, 59.50; H, 6.10; N, 3.85. Found: C, 59.44; H, 6.04; N, 3.80.

Dimethyl (2,3-dihydrobenzo[b][1,4]dioxin-6-yl)(p-tolylamino)methylphosphonate (4e):

Brown Solid, Yield: 95 %, Mp: 197-199 °C. IR (KBr) (νmax, cm-1): 3280 (NH), 1227 (P=O), 753 (P-Caliphatic). 1H NMR (400 MHz, DMSO-d6) δ: 2.32 (3H, s, CH3), 3.57 (3H, d, J = 10.8 Hz, P-OCH3), 3.67 (3H, d, J = 10.4 Hz, P-OCH3), 4.21 (4H, s, OCH2CH2O), 4.64 (1H, d, J = 24.4, P-CH), 6.60 (1H, s, NH), 6.70-7.35 (7H, m, Ar-H). 13C NMR (100.5 MHz, DMSO-d6) δ: 22.5 (Ar-CH3), 52.4 (d, J = 7.2 Hz, P-OCH3), 53.0 (d, J = 7.2 Hz, P-OCH3), 55.8 (d, J = 156.4 Hz, P-CH), 64.0 (C-4 & C-5), 111.9 (C-6), 112.8 (C-3), 114.7 (C-21 & C-61), 119.2 (C-2), 128.6 (C-1), 129.6 (C-31 & C-51), 140.8 (C-11), 142.4 (C-41),146.4 (C-8), 147.0 (C-7). 31P NMR (161.7 MHz, DMSO-d6) δ: 20.6. EI-MS (m/z, %): 364 (M+1, 24), 363 (M+•, 100). Anal.Calcd for C18H22NO5P: C, 51.78; H, 4.86; N, 7.10. Found: C, 51.70; H, 4.78; N, 7.01.

Dimethyl (2,3-dihydrobenzo[b][1,4]dioxin-6-yl)(4-nitrophenylamino)methylphosphonate (4f):

White Solid, Yield: 86 %, Mp: 131-133 °C. IR (KBr) (νmax, cm-1): 3282 (NH), 1520 (N=O), 1228 (P=O), 749 (P-Caliphatic). 1H NMR (400 MHz, DMSO-d6) δ: 3.42 (3H, d, J = 10.6 Hz, P-OCH3), 3.58 (3H, d, J = 10.4 Hz, P-OCH3), 4.24 (4H, s, OCH2CH2O), 4.82 (1H, dd, J = 10.2 Hz, J = 24.4 Hz, P-CH), 6.26-6.30 (1H, m, NH), 6.72-7.19 (7H, m, Ar-H). 13C NMR (100.5 MHz, DMSO-d6) δ: 52.8 (d, J = 7.2 Hz, P-OCH3), 53.4 (d, J = 6.8 Hz, P-OCH3), 54.2 (d, J = 156.4 Hz, P-CH), 64.8 (C-4 & C-5), 113.4 (C-6), 115.7 (C-3), 116.8 (C-21 & C-61), 121.5 (C-2), 125.2 (C-31 & C-51), 128.4 (C-1), 134.4 (C-41), 144.8 (C-8), 145.4 (C-7), 149.4 (C-11). 31P NMR (161.7 MHz, DMSO-d6) δ: 21.1. EI-MS (m/z, %): 395 (M+1, 18), 394 (M+•, 100). Anal.Calcd for C17H19N2O7P: C, 51.78; H, 4.86; N, 7.10. Found: C, 51.71; H, 4.80; N, 7.04.

Dimethyl (2,3-dihydrobenzo[b][1,4]dioxin-6-yl)(3-nitrophenylamino)methylphosphonate (4g):

Brown Solid, Yield: 87 %, Mp: 142-144 °C. IR (KBr) (νmax, cm-1): 3298 (NH), 1242 (P=O), 754 (P-Caliphatic). 1H NMR (400 MHz, DMSO-d6) δ: 3.51 (3H, d, J = 10.8 Hz, P-OCH3), 3.69 (3H, d, J = 10.8 Hz, P-OCH3), 4.18 (4H, s, OCH2CH2O), 4.78 (1H, dd, J = 10.2 Hz, J = 24.4 Hz, P-CH), 6.34-6.38 (1H, m, NH), 6.89-7.48 (7H, m, Ar-H). 13C NMR (100.5 MHz, DMSO-d6) δ: 52.8 (d, J = 7.4 Hz, P-OCH3), 53.42 (d, J = 7.1 Hz, P-OCH3), 54.4 (d, J = 152.8 Hz, P-CH), 64.0 (C-4 & C-5), 106.8 (C-21), 112.7 (C-6), 114.1 (C-3), 114.6 (C-41), 119.2 (C-61), 120.9 (C-2), 125.2 (C-51), 129.2 (C-1), 143.2 (C-31), 144.0 (C-11), 144.4 (C-8), 145.0 (C-7). 31P NMR (161.7 MHz, DMSO-d6) δ: 22.5. EI-MS (m/z, %): 395 (M+1, 18), 394 (M+•, 100). Anal.Calcd for C17H19N2O7P: C, 51.78; H, 4.86; N, 7.10. Found: C, 51.70; H, 4.78; N, 7.01.

Dimethyl (3-chloro-4-fluorophenylamino)(2,3-dihydrobenzo[b][1,4]dioxin-6-yl) methylphosphonate (4h):

Brown Solid, Yield: 91 %, Mp: 128-130 °C. IR (KBr) (νmax, cm-1): 3286 (NH), 1238 (P=O), 754 (P-Caliphatic). 1H NMR (400 MHz, DMSO-d6) δ: 3.45 (3H, d, J = 11.2 Hz, P-OCH3), 3.61 (3H, d, J = 11.4 Hz, P-OCH3), 4.18 (4H, s, OCH2CH2O), 4.42 (1H, dd, J = 10.8 Hz, J = 25.2 Hz, P-CH), 6.23-6.26 (1H, m, NH), 6.76-7.02 (6H, m, Ar-H). 13C NMR (100.5 MHz, DMSO-d6) δ: 52.4 (d, J = 7.8 Hz, P-OCH3), 53.4 (d, J = 7.4 Hz, P-OCH3), 54.8 (d, J = 158.8 Hz, P-CH), 64.8 (C-4 & C-5), 112.7 (C-6), 113.5 (C-3), 115.7 (C-21 ), 117.4 (C-61), 118.2 (C-51), 119.2 (C-2), 121.8 (C-31), 127.8 (C-1), 144.5 (C-11), 145.2 (C-41), 147.2 (C-8), 147.9 (C-7). 31P NMR (161.7 MHz, DMSO-d6) δ: 20.8. EI-MS (m/z, %): 402 (M+2, 35), 401 (M+•, 100). Anal.Calcd for C17H18ClFNO5P: C, 50.82; H, 4.52; N, 3.49. Found: C, 50.76; H, 4.45; N, 3.41.

Dimethyl (2,3-dihydrobenzo[b][1,4]dioxin-6-yl)(4-fluoro-3-nitrophenyl-amino) methylphosphonate (4i):

Yellow Solid, Yield: 89 %, Mp: 101-103 °C. IR (KBr) (νmax, cm-1): 3286 (NH), 1234 (P=O), 752 (P-Caliphatic). 1H NMR (400 MHz, DMSO-d6) δ: 3.44 (3H, d, J = 10.9 Hz, P-OCH3), 3.61 (3H, d, J = 10.5 Hz, P-OCH3), 4.25 (4H, s, OCH2CH2O), 4.52 (1H, d, J = 24.4, P-CH), 6.60 (1H, s, NH), 6.78-7.39 (6H, m, Ar-H). 13C NMR (100.5 MHz, DMSO-d6) δ: 53.0 (d, J = 6.8 Hz, P-OCH3), 53.8 (d, J = 6.4 Hz, P-OCH3), 54.8 (d, J = 152.0 Hz, P-CH), 64.0 (C-4 & C-5), 107.7 (C-21), 111.8 (C-6), 112.4 (C-3), 117.2 (C-51), 119.6 (C-2), 127.1 (C-61), 128.8 (C-1), 134.5 (C-31), 144.1 (C-11), 143.2 (C-41), 145.4 (C-8), 146.2 (C-7). 31P NMR (161.7 MHz, DMSO-d6) δ: 22.4. EI-MS (m/z, %): 412 (M+1, 20), 412 (M+•, 100). Anal.Calcd for C17H18FN2O7P: C, 49.52; H, 4.40; N, 6.79. Found: C, 49.46; H, 4.34; N, 6.72.

Dimethyl (((3,5-dichlorophenyl)amino)(2,3-dihydrobenzo[b][1,4]dioxin-6- yl)methyl)phosphonate (4j):

Green Solid, Yield: 91 %, Mp: 125-127 °C. IR (KBr) (νmax, cm-1): 3290 (NH), 1230 (P=O), 742 (P-Caliphatic). 1H NMR (400 MHz, DMSO-d6) δ: 3.50 (3H, d, J = 10.6 Hz, P-OCH3), 3.62 (3H, d, J = 10.8 Hz, P-OCH3), 4.27 (4H, s, OCH2CH2O), 4.74 (1H, d, J = 24.0, P-CH), 6.64 (1H, s, NH), 6.75-7.38 (6H, m, Ar-H). 13C NMR (100.5 MHz, DMSO-d6) δ: 52.4 (d, J = 7.6 Hz, P-OCH3), 52.9 (d, J = 7.6 Hz, P-OCH3), 54.9 (d, J = 154.8 Hz, P-CH), 64.1 (C-4 & C-5), 112.2 (C-6), 115.5 (C-3), 115.9 (C-21 & C-61), 118.9 (C-41), 120.8 (C-2), 128.8 (C-1), 128.6 (C-31 & C-51), 148.7 (C-11) 144.1 (C-8), 144.8 (C-7). 31P NMR (161.7 MHz, DMSO-d6) δ: 21.2. EI-MS (m/z, %): 419 (M+2, 60), 417 (M+•, 100). Anal.Calcd for C17H18Cl2NO5P: C, 48.82; H, 4.34; N, 3.35. Found: C, 48.74; H, 4.23; N, 3.27.

Dimethyl ((2,3-dihydrobenzo[b][1,4]dioxin-6-yl)((5-methylisoxazol-3-yl)amino) methyl)phosphonate (4k):

Brown Solid, Yield: 87 %, Mp: 135-137 °C. IR (KBr) (νmax, cm-1): 3342 (NH), 1264 (P=O), 758 (P-Caliphatic). 1H NMR (400 MHz, DMSO-d6) δ: 2.36 (3H, s, Ar-CH3), 3.52 (3H, d, J = 10.4 Hz, P-OCH3), 3.64 (3H, d, J = 10.4 Hz, P-OCH3), 4.28 (4H, s, OCH2CH2O), 4.58 (1H, d, J = 24.4, P-CH), 6.68 (1H, s, NH), 6.78-7.28 (4H, m, Ar-H). 13C NMR (100.5 MHz, DMSO-d6) δ: 12.4 (Ar-CH3), 52.7 (d, J = 6.8 Hz, P-OCH3), 53.2 (d, J = 6.4 Hz, P-OCH3), 54.5 (d, J = 154.2 Hz, P-CH), 63.7 (C-4 & C-5), 95.8 (C-31), 114.7 (C-6), 116.4 (C-3), 121.4 (C-2), 129.8 (C-1), 142.8 (C-7), 143.2 (C-8), 150.6 (C-11), 168.5 (C-21). 31P NMR (161.7 MHz, DMSO-d6) δ: 22.7. EI-MS (m/z, %): 355 (M+1, 21), 354 (M+•, 100). Anal.Calcd for C15H19N2O6P: C, 50.85; H, 5.41; N, 7.91. Found: C, 50.77; H, 5.36; N, 7.84.

Dimethyl ((2,3-dihydrobenzo[b][1,4]dioxin-6-yl)(pyridin-4-ylamino)methyl) phosphonate (4l):

Green Solid, Yield: 88 %, Mp: 138-140 °C. IR (KBr) (νmax, cm-1): 3301 (NH), 1262 (P=O), 749 (P-Caliphatic). 1H NMR (400 MHz, DMSO-d6) δ: 3.75 (3H, d, J = 8 Hz, P-OCH3), 3.91 (3H, d, J = 8 Hz, P-OCH3), 4.20 (4H, s, OCH2CH2O), 4.63 (1H, d, J = 24, P-CH), 6.89-6.93 (1H, m, NH), 7.26-8.20 (7H, m, Ar-H). 13C NMR (100.5 MHz, CDCl3) δ: 52.9 (d, J = 6.2 Hz, P-OCH3), 53.3 (d, J = 6.2 Hz, P-OCH3), 54.9 (d, J = 154.3 Hz, P-CH), 63.4 (C-4 & C-5), 114.5 (C-6), 114.7 (C-21 & C-51), 116.5 (C-3), 121.0 (C-2), 129.9 (C-1), 142.6 (C-7), 142.8 (C-8), 143.4 (C-31 & C-41), 155.8 (C-11). 31P NMR (161.7 MHz, DMSO-d6) δ: 20.5. EI-MS (m/z, %): 351 (M+1, 21), 350 (M+•, 100). Anal.Calcd for C16H19N2O5P: C, 54.86; H, 5.47; N, 8.00. Found: C, 54.76; H, 5.41; N, 7.94.

Dimethyl (((6-bromopyridin-2-yl)amino)(2,3-dihydrobenzo[b][1,4]dioxin-6-yl) methyl)phosphonate (4m):

Yellow Solid, Yield: 90 %, Mp: 161-163 °C. IR (KBr) (νmax, cm-1): 3329 (NH), 1258 (P=O), 747 (P-Caliphatic). 1H NMR (400 MHz, DMSO-d6) δ: 3.51 (3H, d, J = 10.6 Hz, P-OCH3), 3.64 (3H, d, J = 10.4 Hz, P-OCH3), 4.25 (4H, s, OCH2CH2O), 4.50 (1H, d, J = 24.2, P-CH), 6.62 (1H, s, NH), 6.94-8.12 (6H, m, Ar-H). 13C NMR (100.5 MHz, DMSO-d6) δ: 52.5 (d, J = 7.0 Hz, P-OCH3), 53.0 (d, J = 6.8 Hz, P-OCH3), 54.2 (d, J = 154.4 Hz, P-CH), 63.4 (C-4 & C-5), 106.2 (C-51), 113.8 (C-6), 115.8 (C-3), 118.4 (C-31), 120.8 (C-2), 131.2 (C-1), 141.5 (C-41), 142.2 (C-21), 143.2 (C-7), 143.8 (C-8), 156.1 (C-11). 31P NMR (161.7 MHz, DMSO-d6) δ: 20.7. EI-MS (m/z, %): 430 (M+2, 100), 428 (M+•, 100). Anal.Calcd for C16H18BrN2O5P: C, 44.77; H, 4.23; N, 6.53. Found: C, 44.68; H, 4.12; N, 6.41.

Dimethyl ((2,3-dihydrobenzo[b][1,4]dioxin-6-yl)((2-methylpyridin-4-yl)amino) methyl)phosphonate (4n):

White Solid, Yield: 89 %, Mp: 125-127 °C. IR (KBr) (νmax, cm-1): 3284 (NH), 1242 (P=O), 758 (P-Caliphatic). 1H NMR (400 MHz, DMSO-d6) δ: 2.28 (3H, s, Ar-CH3), 3.42 (3H, d, J = 10 Hz, P-OCH3), 3.58 (3H, d, J = 10.4 Hz, P-OCH3), 4.19 (4H, s, OCH2CH2O), 4.96 (1H, dd, J = 10.2 Hz, J = 24.4 Hz, P-CH), 6.82-7.98 (1H, m, NH), 6.76-7.02 (6H, m, Ar-H). 13C NMR (100.5 MHz, DMSO-d6) δ: 25.8 (Ar-CH3), 54.2 (d, J = 8.2 Hz, P-OCH3), 54.8 (d, J = 8.2 Hz, P-OCH3), 55.9 (d, J = 154.4 Hz, P-CH), 64.9 (C-4 & C-5), 107.5 (C-51), 108.8 (C-21), 112.5 (C-6), 114.5 (C-3), 119.7 (C-2), 139.8 (C-1), 144.8 (C-7), 145.2 (C-8), 148.8 (C-41), 154.1 (C-11) 156.4 (C-31). 31P NMR (161.7 MHz, DMSO-d6) δ: 21.4. EI-MS (m/z, %): 365 (M+1, 22), 364 (M+•, 100). Anal.Calcd for C17H21N2O5P: C, 56.04; H, 5.81; N, 7.69. Found: C, 56.00; H, 5.75; N, 7.59.

Dimethyl ((benzo[d]thiazol-2-ylamino)(2,3-dihydrobenzo[b][1,4]dioxin-6-yl) methyl)phosphonate (4o):

Brown Solid, Yield: 90 %, Mp: 141-143 °C. IR (KBr) (νmax, cm-1): 3284 (NH), 1232 (P=O), 744 (P-Caliphatic). 1H NMR (400 MHz, DMSO-d6) δ: 3.46 (3H, d, J = 10.4 Hz, P-OCH3), 3.52 (3H, d, J = 10.4 Hz, P-OCH3), 4.24 (4H, s, OCH2CH2O), 4.91 (1H, dd, J = 10.2 Hz, J = 22.8 Hz, P-CH), 6.25-6.28 (1H, m, NH), 7.02-8.21 (7H, m, Ar-H). 13C NMR (100.5 MHz, DMSO-d6) δ: 52.8 (d, J = 7.1 Hz, P-OCH3), 53.4 (d, J = 7.1 Hz, P-OCH3), 54.2 (d, J = 152.4 Hz, P-CH), 64.8 (C-4 & C-5), 114.2 (C-6), 114.8 (C-3), 118.1 (C-51), 119.4 (C-2), 121.8 (C-21), 124.2 (C-31), 125.7 (C-41), 129.5 (C-1), 130.7 (C-71), 142.8 (C-7), 143.2 (C-8), 149.2 (C-61), 174.2 (C-11). 31P NMR (161.7 MHz, DMSO-d6) δ: 20.6. EI-MS (m/z, %): 407 (M+1, 21), 406 (M+•, 100). Anal.Calcd for C18H19N2O5PS: C, 53.20; H, 4.71; N, 6.89. Found: C, 53.10; H 4.76

ANTIOXIDANT ACTIVITY:

DPPH Radical Scavenging Activity

The free radical scavenging activity of α-aminophosphonatesagainst DPPH radical was performed in accordance with Choi et al.2985µM of DPPHwas added to a medium containing different α-aminophosphonates. The medium was incubated for 30 min at room temperature. The decrease in absorbance was measured at 518 nm. Ascorbic acid was used as standard reference to record maximal decrease in DPPHradical absorbance. The values are expressed in percentage of inhibition of DPPHradical absorbance with those of the standard control values without the title compounds (FigureS1) (ascorbic acid maximal inhibition was considered 100 % of inhibition).

DPPH Scavenged (%) =

Where Acont is the absorbance of the control reaction and Atest is the absorbance in the presence of the sample.

In the case of α-aminophosphonates(4a-o), fluoro-nitro substituted compound 4i showed the highest DPPH radical scavenging activity with IC50at 29.8 μg/mL when compared with compounds.

The remaining compounds exhibited DPPH radical scavenging activity in the following order: 4g, (IC50 30.4 μg/mL), 4k, (IC50 32.1 μg/mL), 4f, (IC50 32.9 μg/mL), 4h, (IC50 33.8 μg/mL), 4j, (IC50 39.6 μg/mL), 4n, (IC50 41.4 μg/mL), 4c, (IC50 42.7 μg/mL), 4l, (IC50 45.4 μg/mL), 4b, (IC50 47.6 μg/mL), 4m, (IC50 49.8 μg/mL), 4o, (IC50 50.4 μg/mL), 4e, (IC50 52.6 μg/mL), 4d, (IC50 54.9 μg/mL), 4a, (IC50 58.4 μg/mL) and when compared with ascorbic acid (IC50 32.2 μg/mL).

Figure S1:DPPH Radical Scavenging Activity

Reducing power assay:

The reducing power of synthesized compounds (4a-o)was determined according to the method of Oyaizu et al.30 The compounds having 50 – 100 µM were mixed with 2.5 mL of phosphate buffer (0.2 M, pH 6.6) and 2.5 mL of 1% potassium ferricyanide and incubated at 50C for 20 min. To this mixture 2.5 mL of 10% trichloroacetic acid (TCA) was added and the mixture was centrifuged at 3000 rpm for 20 min. The upper layer (2.5 mL) was mixed with 2.5 mL of deionised water and 0.5 mL of 0.1% Ferric chloride and the UV absorbance was measured at 700 nm using a spectrophotometer. An increase of absorbance of the reaction mixture indicates a higher reducing power. Mean values from three independent samples were calculated for each compound and standard deviations were less than 5 %.

In the case of α-aminophosphonates(4a-o)(FigureS2), derivatives 4g showed the highest reducing power with IC50of 2.08 μg/mL when compared with other compounds. The remaining compounds exhibited reducing power activity in the following order: 4i, (IC50 2.14 μg/mL), 4k, (IC50 2.25 μg/mL), 4f, (IC50 2.74 μg/mL), 4h, (IC50 2.81 μg/mL), 4j, (IC50 2.92 μg/mL), 4n, (IC50 2.98 μg/mL), 4c, (IC50 2.99 μg/mL), 4l, (IC50 3.02 μg/mL), 4o, (IC50 3.06 μg/mL), 4b, (IC50 3.12 μg/mL), 4m, (IC50 3.12 μg/mL), 4a, (IC50 3.36 μg/mL), 4e, (IC50 3.42 μg/mL), 4d, (IC50 3.54 μg/mL) and when compared with ascorbic acid (IC50 2.51 μg/mL).

Figure S2:Reducing power assay

Lipid Peroxidation Assay:

Lipid peroxidation was induced by Fe2+ ascorbate complex system in rat liver cells and was estimated as thiobarbituric acid reacting substances (TBARS) by the method of Ohkawaet al.31Experiments in vitro lipid peroxidation were carried out to clarify the mode of the protective effect of the α-aminophosphonatesagainst oxidative stress-induced cell damage. The inhibition of lipid peroxidation has been used as a model to elucidate antioxidant activity.

According to the results obtained (Figure S3), 4i (IC50 74.4 μg/mL) significantly inhibited the ferric ion plus ascorbic acid in rat liver cells. The remaining compounds exhibited hydroxyl radical scavenging activity in the following order: 4g, (IC50 79.8 μg/mL), 4f, (IC50 80.9 μg/mL), 4k, (IC50 81.8 μg/mL), 4h, (IC50 82.8 μg/mL), 4a, (IC50 83.4 μg/mL), 4j, (IC50 83.5 μg/mL), 4c, (IC50 84.9 μg/mL), 4n, (IC50 85.5 μg/mL), 4l, (IC50 86.4 μg/mL), 4b, (IC50 89.2 μg/mL), 4m, (IC50 89.8 μg/mL), 4e, (IC50 90.2 μg/mL), 4o, (IC50 94.4 μg/mL), 4d, (IC50 96.4 μg/mL) and when compared with ascorbic acid (IC50 81.4 μg/mL).

Figure S3: Lipid Peroxidation Assay

Figure S4: 1H NMR of Compound 4a

Figure S5: 13C NMR of Compound 4a

Figure S6: 31P NMR of Compound 4a

Figure S7: 1H NMR of Compound 4b

Figure S8: 13C NMR of Compound 4b

Figure S9: 31P NMR of Compound 4b

Figure S10: 1H NMR of Compound 4l

Figure S11: 13C NMR of Compound 4l

Figure S12: 31P NMR of Compound 4l