VERFAHREN ZUR HERSTELLUNG VON 4-OXO- 4H-BENZOPYRANDERIVATEN, 4-OXO-4H-BENZOPYRANDERIVATE UND IHRE VERWENDUNG IN FUTTERMITTELN

摘要

1495189 Process for preparation of 4-oxo-4H- benzopyrans and some of which are novel PFIZER Ltd 10 Sept 1976 [12 Sept 1975] 37553/75 Heading C2C The invention comprises a process for preparing compounds of the Formula I wherein R1 is optionally substituted aryl, heteroaryl, cycloalkyl, optionally substituted aralkyl, alkoxy or optionally substituted aryloxy or aryl sulphonyl, R2 is hydrogen or alkyl and the ring A is optionally substituted with, one or more halogen, hydroxy, alkyl or alkoxy, wherein alkyl groups have 1 to 4 carbon atoms, in which a compound of the Formula II is reacted with an N,N-dialkyl or N-alkyl N-aryl amide of formic or a C 2-5 alkanoic acid and a strong acid chloride in the presence of boron trifluoride etherate, followed in the case where ring A is substituted with one or more hydroxyl groups and an amide of a C 2-5 alkanoic acid is used, by hydrolysis of the resulting o-acylated product. Novel compounds of the Formula I are (1) those in which R 2 is hydrogen, R1 is 4-isopropylphenyl, 4-bromophenyl, p-tolyl, 3-chlorophenyl, p-biphenyl or 4-methane sulphonylphenyl and A is substituted in the 5- and 7-position by hydroxy, and (ii) those in which R2 is hydrogen and R1 and ring A are as in Formula I other than those in which R1 is phenyl, substituted phenyl or heteroaryl. 5,7 - Diacetyloxy - 3 - p - fluorophenyl - 2- methyl-4-oxo-4H-benzopyran was prepared from the 5,7-dihydroxy compound for identification purposes. Pharmaceutical compositions of the novel compounds I with usual excipients are growth promotors and improve feed efficiency when administered orally or parenterally. Implants, feed additives and feed concentrates are particularly mentioned.