A new and efficient synthesis of 1,3,4-oxadiazole derivatives using TBTU

A Useful Synthesis of 2-Acylamino-1,3,4-oxadiazoles from Acylthiosemicarbazides Using Potassium Iodate and the Discovery of New Antibacterial Compounds

“…1 . The previous methods for the synthesis of 2-acylamino-1,3,4-oxadiazoles: ( a ) Two-step procedure to synthesize 2-acylamino-1,3,4-oxadiazoles by cyclization and amidization [22,23,24,25,26,27,28,29,30,31,32,33,34,35]; ( b ) One-step procedure to synthesize 2-acylamino-1,3,4-oxadiazoles by desulfurated cyclization [11,36,37,38,39,40,41]. 2 .…”

“…Other desulfurization reagents such as stoichiometric mercuric salts [11,39], or lead oxide [40] can be used to induce the cyclization to form the 2-acylamino-substituted 1,3,4-oxadiazoles. More recently, Balalaie and co-workers [41] proved that O -(benzotriazol-1-yl)- N,N,N′,N′ -tetramethyluronium tetrafluoroborate (TBTU) as a uronium coupling reagent can selectively activate the sulfur moiety to construct disubstituted 1,3,4-oxadiazoles with good yields (Scheme 1). However, these methods suffer from several limitations, such as the handing of harsh and toxic reagents, a poor functional group tolerance, multistep synthetic steps, a long reaction time, and a tedious purified process.…”

T3P as an efficient cyclodehydration reagent for the one-pot synthesis of 2-amino-1,3,4-oxadiazoles

“…15 The other important approach includes S N Ar substitution of oxadiazol-2-ones by activation using the phosphonium reagent (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP). 13 A variety of peptide coupling reagents such as DCC 12 14 have been engaged as the cyclodesufurizers, however their role in cyclodehydration is very limited and only an example of using DCC under microwave irradiation is known. 12 The disadvantages of using coupling reagents are the need for large excess (at least 3 equiv.)…”

Recent advances on oxadiazole motifs: Synthesis, reactions and biological activities

“…It gave a high yield of 85% in 12 hrs. This was even better than the use of alternative desulfurization agents under the same conditions such as p-TsCl/py, Hg(OAc)2, Zn(OAc)2 and Cu(OAc)248 . Cyclodesulphurization of thiosemicarbazide using TBTU2.3.11.…”