PROCEDEU DE PREPARARE A DERIVATILOR DE BENZOXAZOL

摘要

1491863 Benzoxazoles LILLY INDUSTRIES Ltd 22 Oct 1974 [23 Oct 1973] 49260/73 Heading C2C [Also in Division A5] Novel benzoxazoles of the general formula wherein the -CR1R2R3 group is in the 5- or 6- position of the benzoxazole nucleus, R1 is a hydrogen or halogen atom or a C 1-6 alkyl group, R2 is a hydrogen or halogen atom or a C 1-6 alkyl, hydroxy, C 1-6 alkoxy, C 2-7 acyloxy or NR11R12 group, in which R11 is a hydrogen atom or C 1-6 alkyl group and R12 is a hydrogen atom or C 1-6 alkyl or C 2-7 acyl group, R3 is a carboxy group or a salt, ester, amide or hydroxamic acid derivative thereof or a 5-tetrazolyl or 4-R13- 4-R14-2-oxazolinyl group, in which each of R13 and R14 is a hydrogen atom or C 1-6 alkyl or C 1-6 hydroxyalkyl group, R4 is a phenyl group optionally substituted by at least one C 1-6 alkylsulphonyl, C 1-6 alkyl, C 1-6 alkoxy, C 1-6 haloalkyl, C 2-7 acyl, nitro, amino, hydroxy or halogen radical or in two adjacent positions by a methylene- or ethylene-dioxy group and A is CH 2 , CO or CHOR, in which R is a hydrogen atom or C 1-6 alkyl or C 2-7 acyl group, are prepared by cyclizing an o-aminophenol of the general formula wherein Z is R3, a hydrogen or halogen atom or a nitrile group, in the presence of a cyolizing agent of the formula R4-A-COOH, (R4-A-CO) 2 O, R4-A-COCl, R4-A-CONH 2 , R4-A-CONHNH 2 , R4-A-CN or R4-A-CHO and, where necessary, converting Z to R3 by halogenating to convert hydrogen to halogen, by reacting with an alkali metal cyanide to convert halogen to a nitrile group, by hydrolysing to convert a nitrile group to a carbamoyl group, by hydrolysing to convert a nitrile or carbamoyl group to a carboxy group, by reacting with an alcohol under acidic conditions to convert a nitrile group to an esterified carboxy group, and optionally reacting an esterified carboxy group with hydroxylamine to convert the esterified carboxy group to a hydroxamic acid derivative, by reacting with ammonium azide to convert a nitrile group to a 5-tetrazolyl group, or optionally by reacting with an amino alcohol of formula H 2 N-CR13R14-CH 2 OH to convert a carboxy group to a 4-R13-4-R14-2-oxazolinyl group. The corresponding nitriles (R3 is a cyano group) are prepared in the same way. 2,6-Dichlorophenylacetyl chloride is prepared by treating the corresponding free acid with thionyl chloride. 2-(3-Phenylacetamido-4-hydroxy phenyl) propionitrile is prepared by reacting 2-(3-amino-4-hydroxyphenyl) propionitrile with phenylacetyl chloride.