GB803803A - Thiochromones and thioxanthones - Google Patents

Abstract

Thiochromones and thioxanthones are produced by condensing a thiophenol with an a -acyl fatty acid ester in the presence of an amount of polyphosphoric acid at least equal to the amount of thiophenol, at a temperature between 15 DEG and 150 DEG C., preferably between 40 DEG and 100 DEG C. The thiophenol may have the formula: <FORM:0803803/IV (b)/1> wherein X is at least one alkyl and/or acylamino and/or alkoxy radical having 1-4 carbon atoms. The a -acyl fatty acid ester may have the formula R-CO-CHR1-COOR11, wherein R is hydrogen, alkyl, cycloalkyl, aryl or heteroaryl, R1 is hydrogen, alkyl or aryl, and R11 is an alkyl radical containing 1-3 carbon atoms, or may have the formula: <FORM:0803803/IV (b)/2> wherein the group: <FORM:0803803/IV (b)/3> is part of a homocyclic or heterocyclic ring and R11 is an alkyl radical containing 1-3 carbon atoms. The products have the formula: <FORM:0803803/IV (b)/4> Examples describe the preparation of: (1) 2 - methylthiochromone; (2) 2,3 - dimethyl-thiochromone; (3) 2,5,8 - trimethylthiochromone; (4) 2,8 - dimethyl - 5 - acetaminothiochromone, which is saponified to give 2,8-dimethyl - 5 - aminothiochromone; (5) 2,3,8 - trimethyl - 5 - acetaminothiochromone; (6) thioflavone; (7) 2 - methyl - 5,8 - dimethoxythiochromone; (8) 3 - methylthiochromone; (9) 3 - phenylthiochromone; (10) 2 - phenyl - 5-acetamino - 8 - methylthiochromone, which is saponified to give the hydrochloride of 2-phenyl-5 - amino - 8 - methylthiochromone, and similarly 2 - (31 - nitrophenyl) -, 2 - (41 - nitrophenyl) - 2 - (21 - chlorophenyl) - 2 - (41 - chlorophenyl) - and 2 - (41 - methoxyphenyl) - 5-amino - 8 - methylthiochromones; (11) 2-phenyl - 5,8 - dimethyl thiochromone; (12) 1,2,3,4 - tetrahydrothioxanthone, and 1,2,3,4-tetrahydro - 7 - aminothioxanthone after deacylation of the 7 - acetamino compound; (13) 1,2,3,4 - tetrahydro - 5 - methyl - 8 - acetaminothioxanthone, which is hydrolysed to the -8 amino compound, and similarly 1,2,3,4-tetrahydro - 2,5 - and 3,5 - dimethyl - 8 - aminothioxanthone; (14) 1,2 - dihydro - 3,5 - dimethyl - 8 - acetaminothioxanthone, which is hydrolysed to the 8-amino compound; (15) 2,3-trimethylene - 5 - acetamino - 8 - methylthiochromone, which is deacylated; (16) 1,2,3,4-tetrahydro - 5 - methyl - 8 - acetamino - 2,10-dithiaxanthone, which is deacylated; (17) 2-phenyl - 5,8 - dimethoxythiochrome and 2-(41 - methoxyphenyl) - 5,8 - dimethoxythiochromone; (18) 2 - (41 - pyridyl) - thiochromone and 2 - (41 - pyridyl) - 5,8 - dimethylthiochromone; (19) 2 - cyclohexyl - 5 - acetamino-8 - methylthiochromone, which is de - acylated; (20) 1,2,3,4 - tetrahydro - 5,8 - dimethoxythioxanthone; (21) 2 - (31 - pyridyl) - thiochromone and 2 - (31 - pyridyl) - 5,8 - dimethylthiochromone; (22) 2 - (a - thienyl) thiochromone and 2-(a -thienyl) 5-acetamino-8-methylthiochromone, which is de-acylated. The 2-methyl-5-acetaminothiophenol used as starting material for Example 4 is prepared by zinc dust reduction of the sulphochloride from p-acetyltoluidine and chlorosulphonic acid.