Alkyl esters of 3-(3,4-dihalophenyl)-2,6-dioxopiperidine-3-propionic acid of use as intermediates
View Patent ↗The invention relates to lower-alkyl esters of 3-(3,4-dihalophenyl)-2,6-dioxopiperidine-3-propionic acid derivatives, and to processes for preparing the same.
1. A process for the preparation of a compound of formula:
in which R 1 represents a linear C 1 -C 4 -alkyl and X represents a halogen which comprises treating, with an enzyme, a compound of formula:
2. A process according to claim 1 wherein the enzyme is chosen from lipases, esterases and proteases.
3. A process according to claim 2 wherein the enzyme is Candida cylindracea or Candida rugosa lipase or esterase, separately or as a mixture.
4. A compound of formula:
wherein X represents a halogen, and R 1 represents a linear C 1 -C 4 -alkyl.
5. A compound of formula:
in which X represents a halogen.
6. A process for the preparation of a compound of formula (VII):
wherein X represents a halogen, which comprises hydrolyzing a compound of S configuration corresponding to the formula
in which X represents a halogen and R 1 represents a linear C 1 -C 4 alkyl.
7. A process for the preparation of a compound of formula (VIII):
wherein X represents a halogen, which comprises reducing a compound of S configuration corresponding to the formula
in which X represents a halogen and R 1 represents a linear C 1 -C 4 alkyl in the presence of a reducing agent.
8. A process for the preparation of a compound of the formula (IX):
wherein X represents a halogen, which comprises reducing a compound according to claim 4 in the presence of an alkaline hydride.
9. A process for the preparation of a compound of formula (X):
wherein X represents a halogen, which comprises cyclizing a compound according to claim 5 .