4H-Imidazo[2,1-c][1,4]benzoxazine-2-carboxylic acid (3) was found to possess potent activity in the IgE-induced rat passive cutaneous anaphylaxis model which may be predictive of clinical antiallergic activity. Compared to disodium cromoglycate (DSCG, 1), 3 was less active following iv administration but unlike DSCG showed very significant oral activity. To explore the structural requirements for this activity, a range of tricyclic compounds was prepared and their activities were measured. Individual 2-carboxylic acids derived from imidazo[1,2-a]quinolines, imidazo[1,2-a]quinoxalines, imidazo[1,2-a]quinoxalinones, pyrrolo[1,2-a]quinoxalinones, pyrrolo[2,3-a]quinoxalinones, and imidazo[2,1-b]benzothiazoles showed iv activities up to 10(3) times as potent as DSCG and many of them showed significant oral activity. From these, imidazo[1,2-a]quinoxaline-2-carboxylic acid 114 has been chosen for further development.
The solution was kept 1 hr. at -50°and warmed gradually over 2 hr. to -10°C. The liquid was washed with 300 ml. of 10% sodium sulfite, twice with water, and dried over anhydrous sodium sulfate. After evaporating chloroform, 151 g. (75%) of colorless 5,6-dichloro-l,3dioxepane boiling at 56°at 1 mm. was obtained.
decreased in the order of greater substitution of the amine group--i.e., 3" < 2' < 1". These results suggest that 111 is being catalytically deconiposed to IV and hydrogen.8 Ph3SnH -Ph3SnSnPhs + HP Experimental Allylamine and 111.-To a round bottom flask equipped with a stirrer, reflux condenser, gas inlet tube, and gas exit tube leading from the top of the condenser to a trap containing 95y0 ethanol kept a t -78" were added 32.2 g. (0.092 mole) of triphenyltin hydride and 2.6 g. (0.046 mole) of allylamine. Evolution of a gas was observed on mixing. The reaction mixture was stirred under a nitrogen atmosphere til solidification was complete. The contents of the trap gave a negative test with Nessler's reagent for ammonia, no characteristic brown-red color being observed. The solid in the flask was recrystallized from benzene, m.p. 230-232'. It did not depress the melting point on admixture with an authentic sample of 117.In a second experiment, using the same procedure as described above, 20 g. (0.057 mole) of I11 and 1.62 g. (0.029 mole) of I were used. Any possible propylene being evolved was led from the top of the condenser into a trap containing I-hexene kept at -78", but no propylene was detected upon running the trap contents into a vapor phme chromatograph.Benzylamine and 111.-The procedure of Kupchik and Connolly was followed. The first few drops of distillate collected showed bands in the infrared (cm.-l) a t 3077,
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