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Synlett 2003(10): 1459-1462
DOI: 10.1055/s-2003-40844
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Bis(1,3,4-Thiadiazolo)-1,3,5-triazinium Halides: Access to Highly Substituted Aromatic Guanidines [1]

Kurt Wermanna, Martin Walthera, Helmar Görlsb, Ernst Anders*a
a Institut für Organische Chemie und Makromolekulare Chemie der Friedrich-Schiller-Universität, Lessingstrasse 8, 07743 Jena, Germany
b Institut für Anorganische und Analytische Chemie der Friedrich-Schiller-Universität, Lessingstrasse 8, 07743 Jena, Germany
Fax: +49(3641)948212; e-Mail: Ernst.Anders@uni-jena.de;
Further Information

Publication History

Received 22 May 2003
Publication Date:
24 July 2003 (online)

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Abstract

The reaction of bis(1,3,4-thiadiazolo)-1,3,5-triazinium halides with primary aromatic amines in CHCl3/Et3N yields new highly substituted aromatic guanidines (up to 90% yield).

Key words

guanidinylation - nitrogen heterocycles - nucleophilic addition - rearrangements - sulfur heterocycles

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See ref. [5] [7a] [8] and literature cited therein.

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The iminium salt 8a (R1 = 4-MePh; R2 = Me): Identification by HMQC experiments showing a CH correlation between δ = 160.7 and 8.45 ppm. 1H NMR (400 MHz, CDCl3): δ = 2.34 (s, 3 H, CH3), 2.46 (s, 3 H, CH3), 7.79 (d, 2 H, aryl-CH), 7.25 (d, 2 H, aryl-CH), 7.31 (br s, 1 H, NH), 8.45 (s, 1 H, imine-CH). 13C NMR (100.6 MHz, CDCl3): δ = 17.5, 21.7, 129.2, 129.3, 132.8, 142.6, 150.9, 160.7 (imine-CH, broad), 170.0.

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The hydrolysis products 9 and 10 were unambiguously identified by TLC (EtOAc), GC, derivatization with 2,4-dinitrophenylhydrazine, and 1H and 13C NMR spectroscopy in DMSO-d 6.

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General Procedure for the Preparation of Guanidines 6: To a well-stirred mixture of the corresponding bis-(1,3,4-thiadiazolo)-1,3,5-triazinium halide 1 (5 mmol) and amine 2 (5 mmol) in 30 mL CHCl3, Et3N (30 mL) was added gradually at r.t. After stirring over a period of 24 h, the resulting suspension was concentrated in vacuo. The residue was washed with cold water and extracted three times with CHCl3. The combined extracts were dried with Na2SO4 and concentrated in vacuo. The residues were purified by column chromatography (silicagel 60; eluting with EtOAc; pentane/EtOAc; Et2O/EtOAc) or by fractional crystallization from EtOH, MeCN, EtOAc.
All new compounds 6 were fully characterized. Selected analytical data:
5-Methyl-2-(4-methylphenyl)- N ′-(5-methyl-1,3,4-thiadiazol-2-yl)- N -phenyl-1,3,4-thiadiazole-3(2 H )-carboximidamide (6a): Recrystallized from EtOH. 1H NMR (250 MHz, CDCl3): δ = 2.00 (s, 3 H, CH3), 2.26 (s, 3 H, CH3), 2.44 (s, 3 H, CH3), 7.19 (s, 1 H, 2-CH), 6.96-7.22 (m, 9 H, CHph), 10.04 (s, 1 H, NH). 13C NMR (62.9 MHz, CDCl3): δ = 16.1, 16.6, 21.2, 72.0, 122.4, 124.3, 126.6, 128.6, 129.4, 137.7, 138.6, 139.1, 147.9, 149.0, 158.5, 173.1. MS (DCI/H2O): m/z (%) = 409 (100) [C20H21N6S2]+. Anal. Calcd for C20H20N6S2 (408.53): C, 58.80; H, 4.93; N, 20.57; S, 15.69. Found: C, 58.54; H, 5.08; N, 20.62; S, 15.53.
5-Methyl-2-(4-methylphenyl)- N ′-(5-methyl-1,3,4-thiadiazol-2-yl)- N -(4-methylphenyl)-1,3,4-thiadiazole-3(2 H )-carboximidamide (6b): Recrystallized from MeCN. 1H NMR (250 MHz, CDCl3): δ = 2.12 (s, 3 H, CH3), 2.26 (s, 3 H, CH3), 2.32 (s, 3 H, CH3), 2.49 (s, 3 H, CH3), 7.12 (s, 1 H, 2-CH), 6.95-7.26 (m, 8 H, CHph), 10.03 (s, 1 H, NH). 13C NMR (62.9 MHz, CDCl3): δ = 16.8, 17.0, 21.3, 21.6, 72.3, 122.8, 126.9, 129.6, 129.7, 134.4, 136.8, 138.2, 139.0, 148.1, 148.7, 155.2, 173.5. MS (DCI/H2O): m/z (%) = 423(100) [C21H23N6S2]+. Anal. Calcd for C21H22N6S2 (422.56): C, 59.69; H, 5.25; N, 19.89; S, 15.17. Found: C, 59.58; H, 5.33; N, 20.28; S, 15.05.
5-Methyl-2-(4-methylphenyl)- N ′-(5-methyl-1,3,4-thiadiazol-2-yl)- N -(3-nitrophenyl)-1,3,4-thiadiazole-3(2 H )-carboximidamide (6c): Purified by column chromatography. 1H NMR (250 MHz, CDCl3): δ = 1.99 (s, 3 H, CH3), 2.23 (s, 3 H, CH3), 2.49 (s, 3 H, CH3), 6.96 (s, 1 H, 2-CH), 7.19-7.87 (m, 8 H, CHph), 10.59 (s, 1 H, NH). 13C NMR (62.9 MHz, CDCl3): δ = 16.5, 16.9, 21.6, 72.2, 117.4, 118.9, 125.5, 127.7, 127.9, 129.5, 137.6, 138.4, 141.0, 148.4, 148.6, 149.5, 159.7, 173.7. MS (DCI/H2O): m/z (%) = 454 (81) [C20H20N7O2S2]+. Anal. Calcd for C20H19N7O2S2 (453.53): C, 52.97; H, 4.22; N, 21.62; O, 7.06; S, 14.14. Found: C, 52.80; H, 4.38; N, 21.57; S, 13.83.
5-Methyl-2-(4-methylphenyl)- N ′-(5-methyl-1,3,4-thiadiazol-2-yl)- N -(4- t -butylphenyl)-1,3,4-thiadiazole-3(2 H )-carboximidamide (6d): Purified by column chromatography and recrystallized from Et2O. 1H NMR (250 MHz, CDCl3): δ = 1.32 (s, 9 H, CH3), 2.11 (s, 3 H, CH3), 2.36 (s, 3 H, CH3), 2.53 (s, 3 H, CH3), 7.01-7.16 (AA′/XX′, 4 H, CHph), 7.13 (s, 1 H, 2-CH), 7.27-7.29 (AA′/XX′, 4 H, CHph), 10.02 (br s, 1 H, NH). 13C NMR (62.9 MHz, CDCl3): δ = 16.1, 16.6, 21.2, 31.3, 34.4, 72.0, 122.1, 125.5, 126.4, 129.4, 136.3, 137.8, 138.6, 147.4, 147.8, 149.2, 158.7, 173.0. MS (DCI/H2O): m/z (%) = 465(100) [C24H29N6S2]+. Anal. Calcd for C24H28N6S2 (464.65): C, 62.04; H, 6.07; N, 18.09; S, 13.80. Found: C, 61.98; H, 6.47; N, 18.40; S, 13.93.
5-Methyl-2-(4-methylphenyl)- N ′-(5-methyl-1,3,4-thiadiazol-2-yl)- N -(4-methoxyphenyl)-1,3,4-thiadiazole-3(2 H )-carboximidamide (6e): Recrystallized from EtOAc. 1H NMR (250 MHz, CDCl3): δ = 2.10 (s, 3 H, CH3), 2.32 (s, 3 H, CH3), 2.54 (s, 3 H, CH3), 3.81 (s, 3 H, OCH3), 6.78-7.00 (AA′/XX′, 4 H, CHph), 7.11 (s, 1 H, 2-CH), 7.15-7.26 (AA′/XX′, 4 H, CH), 10.08 (br s, 1 H, NH). 13C NMR (62.9 MHz, CDCl3): δ = 16.5, 17.0, 21.5, 55.8, 72.4, 114.2, 124.9, 126.9, 129.7, 132.5, 138.3, 139.0, 147.9, 150.0, 157.1, 159.1, 173.7. MS (DCI/H2O): m/z (%) = 439 (439) [C21H23N6OS2]+. Anal. Calcd for C21H22N6OS2 (438.56): C, 57.51; H, 5.06; N, 19.16; O, 3.65; S, 14.12. Found: C, 57.47; H, 5.31; N, 19.10; S, 14.24.
5-Methyl-2-(4-methylphenyl)- N ′-(5-methyl-1,3,4-thiadiazol-2-yl)- N -(2-methoxyphenyl)-1,3,4-thiadiazole-3(2 H )-carboximidamide (6f): Recrystallized from EtOAc. 1H NMR (250 MHz, CDCl3): δ = 2.12 (s, 3 H, CH3), 2.38 (s, 3 H, CH3), 2.53 (s, 3 H, CH3), 3.88 (s, 3 H, OCH3), 6.76-7.29 (m, 8 H, CHph, 1 H, 2-CH), 9.71 (br s, 1 H, NH). 13C NMR (62.9 MHz, CDCl3): δ = 16.1, 16.5, 21.5, 56.1, 72.2, 110.9, 120.6, 122.9, 125.0, 126.7, 128.5, 129.7, 138.3, 138.9, 148.3, 149.2, 151.2, 159.2, 172.8. MS (DCI/H2O): m/z (%) = 439 (100) [C21H23N6OS2]+. Anal. Calcd for C21H22N6OS2 (438.56): C, 57.51; H, 5.06; N, 19.16; S, 14.12. Found: C, 56.91; H, 5.32; N, 18.67; S, 14.04.
2-Butyl-5-methyl-2- N ′-(5-methyl-1,3,4-thiadiazol-2-yl)- N -phenyl-1,3,4-thiadiazole-3(2 H )-carboximidamide (6g): Purified by column chromatography. 1H NMR (250 MHz, CDCl3): δ = 0.91 (t, 3 H, CH3), 1.21-1.40 (m, 4 H, CH2), 1.89-2.21 (m, 2 H, CH2), 2.06 (s, 3 H, CH3), 2.57 (s, 3 H, CH3), 6.18-6.22 (t, 1 H, 2-CH), 7.02-7.29 (m, 5 H, CHph), 9.86 (s, 1 H, NH). 13C NMR (62.9 MHz, CDCl3): δ = 14.3, 16.5, 17.2, 22.4, 27.1, 36.7, 71.7, 122.6, 124.7, 129.0, 139.5, 149.5, 150.1, 159.1, 173.4. MS (DCI/H2O): m/z (%) = 375 (100) [C17H23N6S2]+. Anal. Calcd for C17H22N6S2 (374.52): C, 54.52; H, 5.92; N, 22.44; S, 17.12. Found: C, 54.59; H, 6.31; N 22.60; S, 16.75.
2-Butyl-5-methyl-2- N ′-(5-methyl-1,3,4-thiadiazol-2-yl)- N -(2-hydroxyphenyl)-1,3,4-thiadiazole-3(2 H )-carboximidamide (6h): Purified by column chromatography. 1H NMR (250 MHz, CDCl3): δ = 0.91 (t, 3 H, CH3), 1.28-1.40 (m, 4 H, CH2), 2.07-2.21 (m, 2 H, CH2), 2.16 (s, 3 H, CH3), 2.56 (s, 3 H, CH3), 6.75-6.81 (t, 1 H, 2-CH), 6.93-7.07 (m, 4 H, CHph), 6.17 (s, 1 H, NH), 8.94 (s, 1 H, OH). 13C NMR (62.9 MHz, CDCl3): δ = 14.1, 16.5, 17.1, 22.7, 26.9, 36.4, 71.3, 117.6, 120.3, 125.3, 126.9, 127.5, 150.8, 151.2, 151.3, 159.6, 172.7. MS (DCI/H2O): m/z (%) = 391(100) [C17H23N6OS2]+. Anal. Calcd for C17H22N6OS2 (390.52): C, 52.29; H, 5.68; N, 21.52; O, 4.10; S, 16.42. Found: C, 51.76; H, 5.88; N, 21.53; S, 16.29.
5-Methyl-2-naphthyl- N ′-(5-methyl-1,3,4-thiadiazol-2-yl)- N -phenyl-1,3,4-thiadiazole-3(2 H )-carboximidamide (6i): Purified by column chromatography. 1H NMR (250 MHz, CDCl3): δ = 2.10
(s, 3 H, CH3), 2.44 (s, 3 H, CH3), 7.09-7.95 (m, 12 H, CHph;naphthyl), 7.95 (s, 1 H, 2-CH), 10.03 (s, 1 H, NH). 13C NMR (62.9 MHz, CDCl3): δ = 16.4, 17.1, 69.8, 123.0, 123.1, 124.2, 124.8, 125.9, 126.3, 126.9, 129.0, 129.5, 129.6, 129.8, 134.4, 136.1, 139.5, 149.3, 149.8, 159.4, 173.3. MS (DCI/H2O): m/z (%) = 445 (100) [C23H21N6S2]+. Anal. Calcd for C23H20N6S2 (444.57): C, 62.14; H, 4.53; N, 18.90; S, 14.42. Found: C, 61.90; H, 4.60; N, 19.25; S, 14.32.
5-Methyl-2-naphthyl- N ′-(5-methyl-1,3,4-thiadiazol-2-yl)- N -(4- t -butylphenyl)-1,3,4-thiadiazole-3(2 H )-carboximidamide (6j): Purified by column chromatography. 1H NMR (250 MHz, CDCl3): δ = 1.33 (s, 9 H, CH3), 2.09 (s, 3 H, CH3), 2.42 (s, 3 H, CH3), 7.08-7.29 (AA′/XX′, 4 H, CHph), 7.48-7.93 (m, 7 H, CHnaphthyl), 7.91 (s, 1 H, 2-CH), 9.98 (s, 1 H, NH). 13C NMR (62.9 MHz, CDCl3): δ = 16.2, 17.0, 31.8, 34.8, 69.7, 122.4, 122.7, 123.5, 125.5, 125.6, 125.9, 126.3, 126.8, 129.1, 129.2, 134.4, 136.1, 136.6, 147.9, 149.5, 149.8, 159.7, 173.2. MS (DCI/H2O): m/z (%) = 501 (100) [C27H29N6S2]+. Anal. Calcd for C27H28N6S2 (500.67): C, 64.77; H, 5.64; N, 16.79; S, 12.81. Found: C, 64.53; H, 6.14; N, 16.51; S, 12.39.
5-Methyl-2-naphthyl- N ′-(5-methyl-1,3,4-thiadiazol-2-yl)- N -(4-methoxyphenyl)-1,3,4-thiadiazole-3(2 H )-carboximidamide (6k): Recrystallized from EtOH. 1H NMR (250 MHz, CDCl3): δ = 2.10 (s, 3 H, CH3), 2.44 (s, 3 H, CH3), 3.83 (s, 3 H, OCH3), 6.81-7.08 (AA′/XX′, 4 H, CHph), 7.48-7.93 (m, 7 H, CHnaphthyl), 7.89 (s, 1 H, 2-CH). 13C NMR (62.9 MHz, CDCl3): δ = 16.3, 17.1, 55.9, 69.8, 114.2, 123.1, 124.2, 125.2, 126.0, 126.3, 126.8, 129.4, 129.5, 129.6, 132.4, 134.4, 136.3, 149.3, 150.0, 157.3, 159.2, 173.5. MS (DCI/H2O): m/z (%) = 475 (100) [C24H23N6OS2]+. Anal. Calcd for C24H22N6OS2 (474.57): C, 60.74; H, 4.67; N, 17.71; O, 3.37; S, 13.51. Found: C, 60.57; H, 4.87; N, 17.90; S, 13.20.
5-Methyl-2-naphthyl- N ′-(5-methyl-1,3,4-thiadiazol-2-yl)- N -(2-hydroxyphenyl)-1,3,4-thiadiazole-3(2 H )-carboximidamide (6l): Recrystallized from EtOAc. 1H NMR (250 MHz, CDCl3): δ = 2.14 (s, 3 H, CH3), 2.28 (s, 3 H, CH3), 6.79-7.08 (m, 4 H, CHph), 7.49 (s, 1 H, NH), 7.38-7.83 (m, 7 H, CHnaphthyl), 7.95 (s, 1 H, 2-CH), 9.13 (s, 1 H, OH). 13C NMR (62.9 MHz, CDCl3): δ = 16.2, 16.9, 69.1, 118.4, 120.4, 122.7, 123.7, 125.7, 126.1, 126.3, 126.9, 127.0, 128.0, 129.4, 129.9, 134.3, 2 × 135.3, 150.4, 150.6, 151.7, 160.0, 171.5. MS (DCI/H2O): m/z (%) = 461(94) [C23H21N6OS2]+. Anal. Calcd for C17H22N6OS2 (460.57): C, 59.98; H, 4.38; N, 18.25; O, 3.47; S, 13.92. Found: C, 59.57; H, 4.70; N, 18.09; S, 13.71.
5- t -Butyl-2-(2-hydroxyphenyl- N ′-(5- t -butyl-1,3,4-thiadiazol-2-yl)- N -(4- t -butylphenyl)-1,3,4-thiadiazole-3(2 H )-carboximidamide (6m): Recrystallized from Et2O. 1H NMR (250 MHz, CDCl3): δ = 0.99 (s, 9 H, CH3), 1.28 (s, 9 H, CH3), 1.42 (s, 9 H, CH3), 6.84-7.41 (m, 9 H, CHph, 2-CH), 11.0 (s, br, 1 H, OH), 11.16 (br s, 1 H, NH). 13C NMR (62.9 MHz, CDCl3): δ = 28.8, 31.1, 31.7, 34.8, 36.6, 36.7, 66.4, 119.5, 121.3, 123.8, 125.7, 126.4, 129.4, 131.3, 137.0, 148.4, 150.8, 154.9, 163.8, 172.4, 174.3. MS (DCI/H2O): m/z (%) = 551(20) [C29H39N6OS2]+. Anal. Calcd for C29H38N6OS2 (550.78): C, 63.24; H, 6.95; N, 15.26; S, 11.64. Found: C, 63.03; H, 7.43; N, 15.37; S, 11.43.
General Procedure for the Formation of 2-(Het)arylamino-5-methyl-1,3,4-thiadiazoles 7: The suspension of 1 (5 mmol) and amine 2 (10.1 mmol) in pyridine (60 mL) was stirred at r.t. for 24-60 h. [11a] The reaction mixture, changing to a nearly clear solution, was concentrated to dryness in vacuo. The solid residue was washed off with water and recrystallized as described in the literature. [14] [16] The novel compound 7e was purified by column chromatography and fractional crystallization from CHCl3/EtOAc to prepare crystalline material suitable for X-ray investigation.
N -(5-methyl-1,3,4-thiadiazol-2-yl)pyridin-2-amine (7e): Purified by column chromatography and crystallized from EtOAc. 1H NMR (250 MHz, DMSO-d 6): δ = 2.56 (s, 3 H, CH3), 6.94 (t, 1 H, pyridine-5 H), 7.05 (d, 1 H, pyridine-3 H), 7.68 (dd, 1 H, pyridine-4 H), 8.24 (d, 1 H, pyridine-6 H), 11.44 (s, 1 H, NH). 13C NMR (62.9 MHz, DMSO-d 6): δ = 14.6 (CH3), 111.0 (pyridine-5C), 116.5 (pyridine-4C), 138.3 (pyridine-3C), 146.5 (pyridine-6C), 150.9 (pyridine-2C), 156.9 (thiadiazole-5C), 159.9 (thiadiazole-2C). MS (DEI): m/z (%) = 192(100) [ C8H8N4S]+. Anal. Calcd for C8H8N4S (192.2): C, 49.98; H, 4.19; N, 29.14; S, 16.68. Found: C, 50.22; H, 4.18; N, 28.83; S, 16.47.

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CCDC 210984 and 210985 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cambridge Crystallographic Data Centre, 12, Union Road, Cambridge CB2 1EZ, UK; fax: +44(1223)336033; or deposit@ccdc.cam.ac.uk).