Design and synthesis of diaziridinyl quinone thiadiazole hybrids via nitrile sulfide cycloaddition reaction as a key step

A series of novel diaziridinyl quinone thiadiazole hybrids (9a–9j) were synthesized starting from 2-hydroxy-5-methoxybenzoic acid 1 in a 7 step synthetic sequence. The key step in the scheme involves the nitrile sulfide cycloaddition reaction of oxathiazolone 4 with p-tosylcyanide to obtain 1,2,4-thiadiazole derivative 5. We have demonstrated that p-tosyl group of thiadiazole 5 can be displaced with various nitrogen heterocycles to generate unknown 3,5-disubstituted thiadiazole derivatives.