1. Regioselective synthesis of 2-amino-substituted 1,3,4-oxadiazole and 1,3,4-thiadiazole derivatives via reagent-based cyclization of thiosemicarbazide intermediate.
- Author
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Yang SJ, Lee SH, Kwak HJ, and Gong YD
- Subjects
- Cyclization, Magnetic Resonance Spectroscopy, Molecular Structure, Oxadiazoles chemistry, Oxazoles chemistry, Semicarbazides chemistry, Stereoisomerism, Thiadiazoles chemistry, Indicators and Reagents chemistry, Oxadiazoles chemical synthesis, Oxazoles chemical synthesis, Semicarbazides chemical synthesis, Thiadiazoles chemical synthesis
- Abstract
A regioselective, reagent-based method for the cyclization reaction of 2-amino-1,3,4-oxadiazole and 2-amino-1,3,4-thiadiazole core skeletons is described. The thiosemicarbazide intermediate 3 was reacted with EDC·HCl in DMSO or p-TsCl, triethylamine in N-methyl-2-pyrrolidone to give the corresponding 2-amino-1,3,4-oxadiazoles 4 and 2-amino-1,3,4-thiadiazoles 5 through regioselcective cyclization processes. The regioselectivity was affected by both R(1) and R(2) in p-TsCl mediated cyclization. It is shown in select sets of thiosemicarbazide 3 with R(1)(benzyl) and R(2)(phenyl). 2-Amino-1,3,4-oxadiazole 4 was also shown in the reaction of p-TsCl mediated cyclization. The resulting 2-amino-1,3,4-oxadiazole and 2-amino-1,3,4-thiadiazole core skeleton are functionalized with various electrophiles such as alkyl halide, acid halides, and sulfornyl chloride in high yields.
- Published
- 2013
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