123400-74-8Relevant articles and documents
Process for the synthesis of a benzo [ij] quinolizine-2-carboxylic acid derivative
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, (2008/06/13)
Process for preparing 6,7-dihydro-9-fluoro-5-methyl--1-oxo-1H,5H-benzo[ij]quinolizine-2-carboxylic acid (flumequine, I) wherein, 6-fluoro-2-methyl-1,2,3,4-tetrahydroquinoline (II) is reacted in the presence of a catalyst with an alkyl ortho-formate (IX), wherein R3 represents a C1-C4 alkyl, and with a 2,2-disubstituted 1,3-dioxan-4,6-dione, wherein each R1 and R2, which can be the same or different, represents a hydrogen atom, a branched- or straight-chain C1-C6 alkyl or phenyl, or R1 and R2 together represent a polymethylene group -(CH2)n-, n= 4 or 5, so as to form a 2,2-disubstituted 5- [1-(6-fluoro-2-methyl--1,2,3,4-tetrahydroquinolyl)] methylene-1,3-dioxan--4,6-dione of formula (VII): and then said compound of formula (VII) is reacted in the presence of polyphosphoric acid and ethyl polyphosphate, whereby the desired compound (I) is directly obtained and isolated according to conventional methods.