An Efficient One-Pot Synthesis of 5-(substituted amino)-1,2,4-thia- and -oxa-diazoles

Abstract

A general protocol for the synthesis of 5-(substituted amino)-1,2,4-thiadiazoles by the cyclocondensation reaction of amidoximes with N-substituted thioureas in the presence of KF/Al 2 O 3 , and of 5-(cyclohexylamino)-1,2,4-oxadiazoles with DCC in the presence of KF/Al 2 O 3 and thiourea, is described. The structures of the new compounds were elucidated by spectroscopic and physical data, and the crystal structure determination by X-ray diffraction of three examples.

Focused microwave irradiation-assisted synthesis of N-cyclohexyl-1,2,4-oxadiazole derivatives with antitumor activity

“…The NMR spectroscopy was recorded and compared to previously reported data. [5] N Yield 71% (115.6 mg); yellowish solid; mp 188-189 °C {Lit. 176-178 °C} [5] ; R f 0.8 (hexane:EtOAc 7:3).…”

“…[5] N Yield 71% (115.6 mg); yellowish solid; mp 188-189 °C {Lit. 176-178 °C} [5] ; R f 0.8 (hexane:EtOAc 7:3). The NMR spectroscopy was recorded and compared to previously reported data.…”

Sodium Carbonate-Promoted Formation of 5-Amino-1,2,4-thiadiazoles and 5-Amino-1,2,4-selenadiazoles with Elemental Sulfur and Selenium

“…On the basis of the control experiments and previous reports, ,,,, a proposed mechanism for the formation of 3-substituted 5-amino-1,2,4-thiadiazoles and 5-amino-1,2,4-selenadiazoles is outlined in Scheme . In the presence of a base, isocyanide 2 reacts with sulfur powder or selenium powder to give isothiocyanate A or isoselenate C . , For the synthesis of 1,2,4-thiadiazole, a lone pair of electrons on the nitrogen of N -hydroxybenzimidamide attacks the electrophilic carbon of the isothiocyanate to give intermediate B ; subsequent deprotonation from intermediate B , followed by intramolecular cyclization to form the S–N bond, gives the 3-substituted 5-amino-1,2,4-thiadiazole 3 .…”

Electrifying green synthesis: recent advances in electrochemical annulation reactions

“…[158][159][160] etc. 165 It is free of catalysts via the use of elemental sulfur with amidines 166 and hydrazones, 167 and dimerization of thioamides 168 or thiobenzamides with methyl bromocyanoacetate. 169 Yang and co-workers describe a facile and efficient protocol for the synthesis of 3-substituted 5-amino-1,2,4-thiadiazoles 143 that avoids the use of metal catalysts and stoichiometric oxidants (Scheme 39).…”