Bridgehead nitrogen heterocycles. IX. Fused-ring systems derived from fusion of the 1,2,4-thiadiazole system with the isoxazole, 1,3,4-oxadiazole, thiazole, 1,2,4-thiadiazole, and 1,3,4-thiadiazole systems
Bridgehead nitrogen heterocycles. IX. Fused-ring systems derived from fusion of the 1,2,4-thiadiazole system with the isoxazole, 1,3,4-oxadiazole, thiazole, 1,2,4-thiadiazole, and 1,3,4-thiadiazole systems