Process for obtaining 3,7-dialkylxanthines from 3-alkyl-xanthines
AssigneeHoechst-Roussel Pharmaceuticals Inc.
InventorsGerhard Korb, Hans-Wolfram Flemming
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Abstract
Process for obtaining 3,7-dialkylxanthines from 3-alkyl-xanthines 3,7-Dialkylxanthines are obtained from the corresponding 3-alkylxanthines using an alkylating agent in the presence of quaternary ammonium and/or phosphonium compounds and, where appropriate, of additional polyethers in a two-phase mixture.
Claims16
A process for obtaining 3,7-dialkylxanthines of the Formula I ##STR7## where R.sup.1 and R.sup.2, independently of each other, are (C.sub.1 -C.sub.6)-alkyl, which may be straight-chain or branched, wherein a 3-alkylxanthine of the Formula II ##STR8## in which R.sup.1 is (C.sub.1 -C.sub.6)-alkyl, which may be straight-chain or branched,
- (a) is converted in aqueous phase and using a basic agent into its salt and
- (b) this salt is reacted in a two-phase mixture with an alkylating agent with 1 to 6 carbon atoms in the presence of at least one quaternary ammonium compound and/or phosphonium compound of the Formula III or IV ##STR9## where R.sup.3 to R.sup.10 are identical or different and, independently of each other, are
- (a) (C.sub.1 -C.sub.20)-alkyl, which may be straight-chain or branched,
- (b) benzyl or
- (c) phenyl and
- X is an anion.
- wherein the alkylation is carried out in the presence of a linear polyether of the Formula V
- R.sup.11 --O--(Y).sub.n --R.sup.12 (V)
- where R.sup.11 and R.sup.12 are identical or different and, independently of each other, are (C.sub.1 -C.sub.8)-alkyl;
- Y is a radical from the group
- (a) --CH.sub.2 --CH.sub.2 --O-- or
- (b) --CH.sub.2 --CH.sub.2 --CH.sub.2 --O--
- and n is an integer from 1 to 8.
Dependencies are inferred from the claim text.