Patent ID: 7396934

Claim:
A process for preparing 3-fluoroquinolines of formula (I): wherein R 1 , R 2 , R 3 and R 4 , which may be identical or different, represent: a hydrogen atom; a fluorine atom; a linear, branched or cyclic alkyl radical optionally substituted with one to three fluorine atoms, with a group OR 5 in which R 5 represents a linear or branched alkyl radical, a hydrogen atom or a hydroxyl radical-protecting group, or with a group NR′R″ in which R′ and R″, which may identical or different, represent a linear or branched alkyl radical, a hydrogen atom or an amino radical-protecting group; a group OR 6 in which R 6 represents a hydrogen atom, a phenol-protecting group or a linear or branched alkyl radical optionally substituted with one to three fluorine atoms, with OR 5 or with NR′R″ as defined above; a group NR′ 1 R″ 1 in which R′ 1 and R″ 1 have the values of R′ and R″ or represent a linear or branched alkyl radical substituted with one to three fluorine atoms, with a group OR 5 as defined above or with a group NR′R″ as defined above; a group CO 2 R a , in which R a represents a hydrogen atom, a linear or branched alkyl radical or a carboxyl radical-protecting group; a phenyl radical or a heteroaryl radical, optionally substituted with one or more of the substituents mentioned above, said process comprising: a) subjecting a compound of formula (IV): wherein R 1 , R 2 , R 3 and R 4 are as defined above, to a Hofmann degradation, so as to obtain a compound of general formula (III): wherein R 1 , R 2 , R 3 and R 4 are as defined above; b) treating said compound of formula (III) under conditions capable of forming the diazonium salt of general formula (II): wherein R 1 , R 2 , R 3 and R 4 are as defined above; and c) heating said compound of formula (II) in an inert organic solvent to form the compound of formula (I).