GB1046543A - Improvements in or relating to azathiaxanthene derivatives - Google Patents

Abstract

The invention comprises compounds of the general formula <FORM:1046543/C2/1> wherein R1 signifies hydrogen or an alkyl radical containing from 1-4 carbon atoms, R2 signifies a hydrogen or halogen atom and R3 signifies an alkyl radical containing from 1-4 carbon atoms, and their acid addition salts, and the preparation thereof by oxidizing a compound of general formula <FORM:1046543/C2/2> with hydrogen peroxide, an organic peracid, an inorganic peracid or salts thereof, especially with an alkali metal metaperiodate for 4-5 days at room temperature. The acid addition salts may be prepared by addition of an organic or inorganic acid to the above compounds. Pharmaceutical compositions comprise a compound of the first general formula above and an inert diluent for enteral or parentaral administration. The therapeutic compositions are anti-histaminics, antiallergics, narcosis potentiators and adrenolytics. 7 - Halo - 9 - (11 - alkylpiperidylidene - 41) - 4 - aza - thiaxanthenes of the second general formula above (R2 = halogen) are prepared by reacting a 7-halo-4-aza-thiaxanthone with a 1-alkyl-4-piperidyl magnesium halide, hydrolysing the Grignard complex and treating the resulting 7 - halo - 9 - (11 - alkylpiperidyl - 41) - aza-thiaxanthydrol with a dehydrating agent. 7-Halo-4-aza-thiaxanthones are prepared by condensing a 2-chloronicotinic acid with a p-halothiophenol and cyclizing the resulting 3-carboxypyridyl-(2) p-halophenyl sulphide by heating with polyphosphoric acid.