Cis-alkoxy-substituted spirocyclic 1-H-pyrrolidine-2,4-dione derivatives
View Patent ↗Process for preparing cis-alkoxy-substituted spirocyclic 1-H-pyrrolidine-2,4-dione derivatives and alkali metal salts and alkaline earth metal salts thereof.
1. A process for isolating cis-hydantoins of formula (cis-II)
in which
A represents C 1 -C 6 -alkyl,
comprising stirring an isomer mixture of formula (II)
in which A has the meaning mentioned above,
with an aqueous solution of an alkali metal hydroxide or alkaline earth metal hydroxide, and isolating the cis isomer.
2. The process according to claim 1 , where A represents C 1 -C 4 -alkyl.
3. The process according to claim 1 , where A represents methyl, ethyl, propyl, isopropyl, butyl or isobutyl.
4. The process according to claim 1 , where A represents methyl.
5. The process according to claim 1 , wherein lithium hydroxide, sodium hydroxide, potassium hydroxide, cesium hydroxide, magnesium hydroxide, rubidium hydroxide, calcium hydroxide or barium hydroxide is used.
6. A compound of formula (cis-IV)
or a hydrate thereof in which
A represents C 1 -C 6 -alkyl,
M represents an alkali metal cation or represents an alkaline earth metal cation and
n represents 1 if M is an alkali metal cation
or
represents 2 if M is an alkaline earth metal cation.
7. A compound of formula (cis-IV) according to claim 6 , in which
A represents methyl,
M represents Li + , Na + or K + and
n represents 1.
8. A compound of formula (cis-IV) according to claim 6 , in which
M represents Na + and
n represents 1.
9. A compound of formula (cis-IV) according to claim 6 in the form of a hydrate.