1. Heterocyclic ring-closure reactions. 8. Reactions of isothiocyanates with cyanothioformamides. Cyclization of 5-imino-4-thioxo-2-imidazolidones and 5-imino-2,4-imidazolidinedithiones to 5,7-dihydrodiimidazo[4,5-b:4',5'-e]pyrazine-2,6(1H,3H)-diones and -dithiones
2. Heterocyclic ring-closure reactions. 6. Preparation and further cyclization reactions of 5-imino-1,3-diphenyl-4-thioxo-2-imidazolidinone and 5-imino-1,3-diphenyl-2,4-imidazolidinedithione
3. Personal correspondence with Hobie Joyce (at the Union Carbide Co. Technical Center, South Charleston, WA) and S. Singhawangcha (Union Carbide Agricultural Products Co., Research Triangle Park, NC) in 1983.
4. High resolution ms at m/e 365: 364.9611 (Calcd. for C15H9Cl2N3S2: 364.9616). At m/e 288: 288.0099 (Calcd. for C14H8Cl2N3: 288.0096).
5. The chemical shift pattern of these imidazolidinedithiones agrees well with that reported on 1,3-diphenyl-5-imino-2,4-imidazolidinedithione 1 (δ 180.3, 180.2 and 156.4 ppm) in Reference No. 1.