Rapid and efficient microwave-assisted synthesis of 5-amino-3-aralkoxy(methoxy)amino-1,2,4-oxadiazoles

Tetrahedron Letters

Volumn 48, Issue 15, 2007, Pages 2733-2735

  Kurz, Thomas ^a   Lolak, Nabih ^a   Geffken, Detlef ^a  

^a UNIVERSITY OF HAMBURG   (Germany)

Author keywords

1,2,4 Oxadiazoles; Diphenyl N cyanimidocarbonate; Microwave assisted synthesis; N1 Aralkoxy(methoxy) N3 cyano O phenylisoureas; O Substituted hydroxylamines

Indexed keywords

1,2,4 OXADIAZOLE DERIVATIVE; BIPHENYL; DIPHENYL N CYANIMIDOCARBONATE; HYDROXYLAMINE; UNCLASSIFIED DRUG; UREA DERIVATIVE;

ARTICLE; DRUG STRUCTURE; DRUG SYNTHESIS; MICROWAVE RADIATION; SUBSTITUTION REACTION;

EID: 33947151012     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.tetlet.2007.02.058     Document Type: Article

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14. 2: C, 68.31; H, 5.37; N, 14.94. Found: C, 68.10; H, 5.33; N, 14.74.
15. General procedure for the conventional synthesis of 5-amino-3-aralkoxy(methoxy)amino-1,2,4-oxadiazoles 3a-h. To a solution of O-phenylisoureas 2a-h (1 mmol) in methanol (5 mL) was added a solution of hydroxylamine in THF (15 mL)-prepared from hydroxylamine hydrochloride (10 mmol) and triethylamine (10 mmol) in 15 mL of THF. The reaction mixture was stirred for 3-5 h at 50 °C and IR spectra were recorded every 30 min. Afterwards the reaction mixture was allowed to cool to room temperature, the suspension was filtered, the solvent removed under reduced pressure and the resulting oily residue purified by column chromatography using diethyl ether/ethyl acetate (9:1) as an eluent. Analytically pure products have been obtained after recrystallization from THF/petrolether (Table 2).
16. To 1 mmol of compound 3a in a 10 mL glass pressure microwave tube equipped with a magnetic stirrer bar was added a solution of hydroxylamine in THF (5 mL) prepared from hydroxylamine hydrochloride (5 mmol) and triethylamine (5 mmol) in 5 mL of THF. Afterwards the reaction mixture was subjected to microwave irradiation for 1 min. For detailed reaction conditions see Ref. 14.
17. 2: C, 54.54; H, 5.49; N, 25.44. Found: C, 54.35; H, 5.46; N, 25.21.