| 摘要 |
<p>Novel pyran-4-one compounds and a process for their preparation are disclosed. These compounds are useful for the treatment of immediate hypersensitivity diseases such as asthma. The novel pyran-4-one compounds have the following formula (I): (I) in which R1 is COOR5, CONHR5, cyano, 5-tetrazolyl or R6, where R5 is hydrogen or C1-8 alkyl and R6 is phenyl or naphthyl, the phenyl or naphthyl being optionally substituted by one or more groups selected from halogen, C1-6 alkyl, C1-4 alkoxy, hydroxy, benzyloxy, nitro, trifluoromethyl, carboxyl, C1-4 alkylsulphinyl, C1-4 alkylsulphonyl, N(R5)2, NHCOR5 and SR5; R2 is R6 or -CH=CH-R6 when R1 is COOR5, CONHR5, cyano or 5-tetrazolyl, or R2 is -CH=CH-R6 when R1 is R6; R3 is hydrogen, C1-6 alkyl, halogen, hydroxy or -OCH2 R6; and R4 is hydrogen, C1-6 alkyl or halogen; and salts thereof; provided that (i) when R3 is hydrogen, R4 is hydrogen or methyl and R1 is COOR5 or CONHR5 where R5 is hydrogen, methyl or ethyl, R2 is not phenyl, (ii) when R3 and R4 are both hydrogen and R1 is COOR5 where R5 is methyl, R2 is not 2-methoxy-phenyl or 4-methoxyphenyl (iii) when R3 and R4 are both hydrogen and R1 is COOR5 where R5 is ethyl, R2 is not 3,4-di-methoxyphenyl, and (iv) when R3 and R4 are both hydrogen and R1 is phenyl or 4-methoxyphenyl, R2 is not styryl or 4-methoxystyryl.</p> |
