160893-92-5 5H-1,3,4-Thiadiazolo(2,3-b)quinazoline-5-thione, 6,7,8,9-tetrahydro-2-ethyl- 6,7,8,9-Tetrahydro-2-ethyl-5H-1,3,4-thiadiazolo(2,3-b)quinazoline-5-thione