Electrochemically Initiated Oxidative Cyclization: a Versatile Route for the Synthesis

Electrochemically initiated oxidative cyclization: A versatile route for the synthesis of 5-substituted2-amino-1,3,4-oxadiazoles

Sushma Singh∙ Laxmi Kant Sharma∙ Apoorv Saraswat∙ R.K.P. Singh

Supplementary Material:

Spectroscopic data for compounds4a-4k

2-(Phenyl)amino-5-(4-pyridyl)-1,3,4-oxadiazole (4a, C13H10N4O)

1H NMR (400 MHz, CDCl3):  = 6.43-7.0 (m, 5H, Ar-H), 7.57-8.62 (m, 4H, Py-H), 4.0 (br s, 1H, NH) ppm; 13C NMR (100 MHz, CDCl3):  = 115.2, 118.4, 122.2, 129.4, 143.7, 146.6, 147.6, 150.2, 171.8 ppm; IR (KBr): ν= 3,445, 3,045, 1,475, 1,648, 1,239, 1,076, 1,619 cm-1; MS: m/z = 238 (M+).

2-(2-Methyl-phenyl)amino-5-(4-pyridyl)-1,3,4-oxadiazole (4b,C14H12N4O)

1H NMR (400 MHz, CDCl3):  = 2.31 (s, 3H, CH3), 6.31-6.80 (m, 4H, Ar-H), 7.56- 8.62 (m, 4H, Py-H), 4.0 (br s, 1H, NH) ppm; 13C NMR (100 MHz, CDCl3):  = 12.1 (CH3), 115.1, 118.5, 122.1, 124.2, 126.4, 130.1, 143.6, 147.5, 147.3, 150.4, 171.9 ppm; IR (KBr): ν= 2,858, 3,045, 1,470, 1,608, 1,235, 1,086, 1,608, 980, 890, 750, 595 cm-1; MS: m/z = 252 (M+).

2-(4-Methyl-phenyl)amino-5-(4-pyridyl)-1,3,4-oxadiazole (4c,C14H12N4O)

1H NMR (400 MHz, CDCl3):  = 2.33 (s, 3H, CH3), 7.2-7.5 (m, 4H, Ar-H), 7.58-8.62 (m, 4H, Py-H), 4.0 (br s, 1H, NH) ppm; 13C NMR (100 MHz, CDCl3):  = 20.9 (CH3), 115.1, 122.2, 127.6, 143.6, 147.6, 150.4, 171.8 ppm; IR (KBr): ν= 3,155, 3,055, 1,473, 1,628, 1,238, 1,089, 1,602, 985, 890, 755, 597 cm-1; MS: m/z = 252 (M+).

2-(2-Methoxy-phenyl)amino-5-(4-pyridyl)-1,3,4-oxadiazole (4d, C14H12N4O2)

1H NMR (400 MHz, CDCl3):  = 3.75 (s, 3H, OCH3), 6.50-6.56 (m, 4H, Ar-H), 8.2 and 8.5 (m, 4H, Py-H), 4.0 (br s, 1H, NH) ppm; 13C NMR (100 MHz, CDCl3):  = 56.0 (OCH3), 114.9, 116.1, 119.5, 121.6, 122.1, 132.3, 143.7, 147.6, 148.6, 150.3, 171.8 ppm; IR (KBr): ν= 2,895, 3,045, 1,465, 1,608, 1,235, 1,094, 1,620, 960, 865, 765 cm-1; MS: m/z = 268 (M+).

2-(4-Methoxy-phenyl)amino-5-(4-pyridyl)-1,3,4-oxadiazolez (4e, C14H12N4O2)

1H NMR (400 MHz, CDCl3):  = 3.71 (s, 3H, OCH3), 6.32-6.51 (m, 4H, Ar-H), 7.61-8.66 (m, 2H, Py-H), 4.0 (br s, 1H, NH) ppm; 13C NMR (100 MHz, CDCl3):  = 56.0 (OCH3), 114.8, 116.2, 122.2, 139.1, 143.8, 147.6, 150.2, 152.0, 171.8 ppm; IR (KBr): ν= 3,435, 3,045, 1,472, 1,608, 1,236, 1,064, 1,622, 980, 890, 810, 730 cm-1; MS: m/z = 268 (M+).

2-(4-Chloro-phenyl)amino-5-(4-pyridyl)-1,3,4-oxadiazole (4f, C13H9N4OCl)

1H NMR (400 MHz, CDCl3):  = 6.41-7.03 (m, 4H, Ar-H), 7.62-8.66 (m, 4H, Py-H), 4.0 (br s, 1H, NH) ppm; 13C NMR (100 MHz, CDCl3):  = 116.4, 122.2, 123.7, 129.8, 143.8, 144.9, 147.6, 150.4, 171.8 ppm; IR (KBr): ν= 3,255, 3,045, 1,468, 1,615, 1,246, 1,059, 1,622, 728, 960, 765 cm-1; MS: m/z = 268 (M+).

2-(Methyl)amino-5-(2-methoxynaphthalene)-1,3,4-oxadiazole (4g, C14H13N3O2)

1H NMR (400 MHz, CDCl3):  = 2.45 (s, 3H, CH3), 5.25 (s, 2H, CH2), 6.95-7.60 (m, 7H, Naphthyl-H), 4.0 (s, 1H, NH) ppm; 13C NMR (100 MHz, CDCl3):  = 35.0 (CH3), 72.0 (CH2), 105.7, 118.7, 123.6, 126.4, 126.9, 127.6, 129.4, 129.6, 134.7, 147.6, 157.8, 171.8 ppm; IR (KBr): ν= 3,236, 1,667, 1,046, 1,068, 1,609 cm-1; MS: m/z = 255 (M+).

2-(Ethyl)amino-5-(2-methoxynaphthalene)-1,3,4-oxadiazole (4h, C15H15N3O2)

1H NMR (400 MHz, CDCl3):  = 1.00 (t, 3H, CH3), 3.15 (m, 2H, CH2CH3), 5.30 (s, 2H, CH2), 6.97-7.65 (m, 7H, Naphthyl-H), 4.0 (s, 1H, NH) ppm; 13C NMR (100 MHz, CDCl3):  = 15.5 (CH3), 44.1 (CH2), 72 (CH2), 105.9, 118.8, 123.8, 126.3, 126.9, 127.8, 129.2, 129.6, 134.7, 147.6, 157.6, 171.8 ppm; IR (KBr): ν= 3,362, 1,629, 1038, 1,043, 1,612 cm-1; MS: m/z = 269 (M+).

2-(Allyl)amino-5-(2-methoxynaphthalene)-1,3,4-oxadiazole (4i, C16H15N3O2)

1H NMR (400 MHz CDCl3):  = 3.79 (m, 2H, CH2CH=CH2), 5.12 (dd, 1H, CH2CH=CH2), 5.10 (dd, 1H, CH2CH=CH2), 5.28 (s, 2H, CH2), 5.89 (m, 1H, =CH), 6.94-7.68 (m, 7H, Naphthyl-H), 4.0 (s, 1H, NH) ppm; 13C NMR (100 MHz, CDCl3):  = 54.5 (CH2), 72.0 (CH2), 114.8 (CH2), 134.4 (CH), 105.7, 114.8, 118.9, 123.8, 126.3, 126.9, 127.8, 129.2, 129.6, 134.2, 134.7, 147.6, 157.8, 171.8 ppm; IR (KBr):ν= 3,463, 1,633, 1,026, 1,062, 1,618 cm-1; MS: m/z = 281 (M+).

2-(Phenyl)amino-5-(2-methoxynaphthalene)-1,3,4-oxadiazole (4j, C19H15N3O2)

1H NMR (400 MHz, CDCl3):  = 5.25 (s, 2H, CH2), 6.45-7.02 (m, 5H, Ar-H), 6.94-7.68 (m, 7H, Naphthyl-H), 4.0 (s, 1H, NH) ppm; 13C NMR (100 MHz, CDCl3):  = 72.0 (CH2), 105.7, 115.2, 118.4, 118.9, 123.6, 126.3, 126.9, 127.8, 129.2, 129.6, 134.7, 146.8, 147.6, 157.8, 171.8 ppm; IR (KBr): ν = 3,463, 1,651, 1,036, 1,046, 1,602 cm-1; MS: m/z = 317 (M+).

2-(3-Chloro-phenyl)amino-5-(2-methoxynaphthalene)-1,3,4-oxadiazole (4k, C19H14N3O2Cl)

1H NMR (400 MHz, CDCl3):  = 5.25 (s, 2H, CH2), 6.96-7.64 (m, 7H, Naphthyl-H), 6.35-6.94 (m, 5H, Ar-H), 4.0 (s, 1H, NH) ppm; 13C NMR (100 MHz, CDCl3):  = 72.0 (OCH2), 105.7, 113.3, 115.6, 118.7, 118.9, 123.8, 126.3, 126.9, 127.8, 129.2, 129.6, 130.8, 134.7, 147.6, 148.2, 157.8, 171.8 ppm; IR (KBr): ν = 3,400, 1,614, 1,150, 1,042, 1,605, 776 cm-1; MS: m/z = 317 (M+).