Process for preparing 4-hydroxy-2-pyrrolidone

Details Process for preparing 4-hydroxy-2-pyrrolidone Process for preparing 4-hydroxy-2-pyrrolidone

1997-11-19

1999-02-09

Ramsuer, Robert W.

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C07D207273

Patent

active

058696946

DESCRIPTION:

BRIEF SUMMARY
This application is a 371 of PCT/JP96/01259 filed May 14, 1996.


FIELD OF ART

This invention relates to an improved process for preparing 4-hydroxy-2-pyrrolidone useful as an intermediate for medicines, agricultural chemicals, etc.


BACKGROUND OF ART

4-Hydroxy-2-pyrrolidone is used as an intermediate for medicines, agricultural chemicals, etc. The following processes for preparing it are known. These are a process for preparing it from a 183756/1982, Tetrahedron Lett., 41,5603(1985), Japanese Patent Publication No. 176564/1986!, a process for preparing it from a 4-chloro-3-hydroxybutyrate and benzylamine (Japanese Patent Publication No. 45360/1989), a process for preparing it from a cyclobutanone derivative and optically active .alpha.-methylbenzylamine (Synthetic Comm., 21,693(1991), a process for preparing it from 3,4-epoxibutyramide and optically active .alpha.-methylbenzylamine (J. Chem. Research(s), 376, 1990), a process for preparing it by heating and dehydrating 4-amino-3-hydroxybutyric acid (abbreviated to GABOB hereinafter) process for preparing it from optically active GABOB and hexamethyldisilazane (Synthesis, 1978, 614), a process for preparing it from optically active 4-hydroxyproline (Japanese Patent Publication No. 250352/1988) and a process for preparing it from a 4-bromo crotonic acid
These processes, however, have following disadvantages industrially: The process from a 4-chloro-3-hydroxybutyrate and ammonia produces many kinds of by-products and it is difficult to achieve high yield. The process from benzylamine or .alpha.-methylbenzylamine needs debenzylation or demethybenzyllation procedure after constructing a pyrrolidone skeleton and this procedure is so troublesome as it uses an alkali metal in liquid ammonia at low temperature. The process by heating and dehydrating GABOB is low in the yield and in case using an optically active compound, the racemization occurs. The process from optically active GABOB and hexamethyldisilazane is high in the yield, but the hexamethyldisilazane is expensive and the process needs desilylation procedure after constructing pyrrolidone skeleton. The process from optically active 4-hydroxyproline or a 4-bromo crotonic acid ester comprises many steps, and it is not practical. Therefore, a more efficient process for preparing 4-hydroxy-2-pyrrolidone was desired.


DISCLOSURE OF INVENTION

The present inventors engaged extensively in solving the above problems, and found a novel process for preparing the above objective compound from a 4-halogeno-3-hydroxybutyrate and an alkali metal or alkaline earth metal azide.
This invention relates to a process for preparing 4-hydroxy-2-pyrrolidone of the formula ##STR2## by reacting a 4-halogeno-3-hydroxybutyrate of a formula ##STR3## wherein X is a halogen, and R is an C.sup.1 -C.sup.4 alkyl, and an alkali metal or alkaline earth metal azide, to produce a 4-azido-3-hydroxy-butyrate of a formula ##STR4## wherein R is the same as defined above, and then by hydrogenating an azide group of the ester compound in the presence of catalyst and by cyclizing a hydrogenated compound.


BEST MODE OF PRESENT INVENTION

The present invention is explained in detail by showing the reaction scheme. ##STR5##
Examples of 4-halogeno-3-hydroxybutyrates of formula (2) used as a starting material are methyl 4-chloro-3-hydroxybutyrate, ethyl 4-chloro-3-hydroxybutyrate, isopropyl 4-chloro-3-hydroxybutyrate, butyl 4-chloro-3-hydroxybutyrate, t-butyl 4-chloro-3-hydroxybutyrate, methyl 4-bromo-3- hydroxybutyrate, ethyl 4-bromo-3-hydroxybutyrate, isopropyl 4-bromo-3-hydroxybutyrate, butyl 4-bromo-3-hydroxybutyrate, and t-butyl 4-bromo-3-hydroxybutyrate.
Several processes of these starting materials are proposed, and these materials can be prepared by the following known processes: e.g. a process by reacting epichlorohydrin, carbon monoxide and an alcohol (Japanese Patent Publication No. 183749/1982), and a process by reducing a gamma-halo acetoacetate prepared from diketone, a halogen and an alcohol (Japanese Patent Publication No. 157747/19

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