1.2.4- Oxadiazoles, 3-anilino-5-phenyl

I-Cyano-3-phenylurea, first obtained by the alkaline hydrolysis of 5-anilino-3- -toluyl-l,2,4-oxadiazole, has been prepared by tlic condensation of phenyl isocyanate and the sodium salt of cyanamide. However, in these publications an incorrect structural assignment for the product was made. 1-Cyano-3-phenyl-urea is obtained also, together with other products, by warming gently l-cyano-3-phenylthiourea with caustic soda in the presence of ethylene chlorohydrin, or by gradually adding caustic )otash to a boiling solution of 1-phenyldithiobiuret and ethylene clilorohydrin in ethanol. ... 

Morpholino-3-[4-phenyl(thiosemicarbazido)carbonyl]quinoxaline (129) gave 2-morpholino-3-(4-phenyl-5-thioxo-5,6-drhydro-4//-l,2,4-triazol-3-yl)quin-oxaline (130) (2M NaOH, reflux, 3 h 35%), 2-(5-anilino-l,3,4-thiadiazol-2-yl)-3-morpholinoquinoxaline (131, X = S) (98% H2SO4, 0°C, 1 h, then 20°C, 12 h 89%), or 2-(5-anilino-l,3,4-oxadiazol-2-yl)-3-morpholinoquinoxaline (131, X = O) (NaOH, H2O, EtOH, I/Kii dropwise, 5°C 95°C, 4 h 81%) analogs of all three products were made similarly. ... 

Kohlensaure-anilid-(2-benzoyl-hydrazid) reagiert mil Dichlor-triphenyl-phosphoran/Triethyl-amin iiber Benzonitril-(anilinocarbonyl-imin) in einer 1,5-Elektrocyclisierung zu 2-Anilino-5-phenyl-1,3,4-oxadiazol (87% Schmp. 21 4 2 1 5 )420 ... 

Anilino-5 phcnyl-I,3,4-oxadiazol (R = C6IIS)549 Beim Erhitzen von 1,46g (10,0 mmol) 5-Phenyl-tctrazol init 5 ml (40 mmol) Phenyl-isocyanat auf 140-150° werden in 1 h 245 ml Stickstoff freigesetzt. Nach Ab-destillieren des ubcrschiissigen Isocyanats i. Wasserstrahlvak. wird der farblose kristallinc Riickstand aus Elhanol umkristailisiert Ausbeute 2.17g (92%) Schmp. 210-212°. 

Isophthaisaure 2,6-Dimethyl-4-dimethylamino- -bis-nitriloxid E5, 1591 (aus Bis-oxim) Malonsaure (Amino-benzylamino-methylen)- -methylester-nitril E15/2, 2156 (CC13 - NH-R) I,3i4-Oxadiazol 5-Morpholino-2-phenyl- E8c, 573 (Ar — CO — NH-NH-CO-NR2/POCl3) Phthalazine l,4-Dihydroxy-6-pyrrolidino- E9a, 752 (subst. Phthalanhydrid + N2H4) lH-Pyrazol 5-Carboxy-l-methyl-4-(4-methyl-anilino)- E8b, 633 (4-Br -> 4-NH-Ar)... 

The reaction of 5-aryl (hetaryl)tetrazoles (Li) with phenyl isocyanate under the conditions of microwave activation formed the corresponding 2-anilino-5-aryl(hetaryl)-l,3,4-oxadiazoles (Lii) in high yields [43]. 

When the carbon atoms of the NCC sequence were part of an aromatic ring, as in 3-anilino-5-phenyl-l,2,4-oxadiazole (97), no rearrangement was observed.4... 

Bifunctional systems form heterocyclic rings for example (194) yields (195). Photolysis of N-(triphenylmethyl)anilines results exclusively in C-N bond homolysis to give the trityl (< ) = 0.6-0.8) and anilino radicals." Reduction of the N-O bond cleaved intermediate (196) (formed on irradiation of 5-amino or 5-phenyl-1,2,4-oxadiazoles) by sodium hydrogen sulfide, thiols or thioamides yields the corresponding benzamidines (197). In contrast, in the presence of nucleophilic thioureas (199) or thiocarbamates (200), N-S bond formation occurs and subsequent elimination from the possible intermediate (201) yields the thiadia-zoles (198) or (202) respectively. ... 

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