CS253313B1 - Process for preparing (Z) -3- (hydroxymethylene) -dihydro-2 (3H) -furanone sodium salt - Google Patents

Abstract

The subject of the invention is a method for preparing the sodium salt of (Z)-3-(hydromethylene)dihydro-2(3H)-furanone. The sodium salt of (Z)-3-(hydroxymethylene)dihydro-2-(3H)-furanone is prepared according to the invention by treating gamma-butyrolactone and ethyl formate with a strong base, e.g. sodium or sodium hydride or sodium alcoholate, at temperatures of -10 to -30 °C. The sodium salt of (Z)-3-(hydroxymethylene)dihydro-2-(3H)-furanone is a reactive nucleophilic agent, allowing the preparation of pure derivatives of (Z)-3-(hydroxymethylene)dihydro-2(3H)-furanone.

Description

The present invention relates to a process for the preparation of (Z) -3- (hydroxymethylene) dihydro-2 (311) -furanone sodium.

(Z) -3- (hydroxymethylene) dihydro-2 (3H) -furanone sodium, first prepared by Kort and Maohleidt (Ber. Deut. Chem. Ges. 88, 1684 (1955)), is a reactive nucleophilic reagent whose numerous reactions are described in the literature. Due to the unclear configuration of this sodium salt, its reactions usually result in mixtures of (E) - and (Z) -isomers, where the (Z) -isomers are underrepresented and the ratio of isomers is not reproducible.

It has now been found (Jonas J .: Coll. Czech. Chem. Commun. - in press) that 3- (hydroxymethylene) dihydro-2 (3H) -furanone sodium is a polymeric substance whose polymorphism is closely related to the geometric isomerism of the double C = C bond. According to the literature, the prepared sodium salt is excreted as a mixed modification (E + Z) and undergoes conversion to a stable modification (E).

The isomers of the sodium salt were characterized by ¹³ C NMR spectra and IR spectra in nujol, and a method for preparing a modification (Z) containing only the pure isomer of the sodium salt of (Z) -3- (hydroxymethylene) dihydro-2 (3H) -furanone, from from which pure derivatives of the (Z) -configuration can be prepared.

According to the invention, a process for the preparation of pure (Z) -3- (hydroxymethylene) dihydro-2 (3H) -furanone sodium salt of formula I has been found,

H

which permits the use of a configuration-pure compound I for nucleophilic reactions and allows the preparation of pure (Z) -3- (hydroxymethylene) dihydro-2 (3H) -furanone derivatives, such as sulfonates or carboxylates. The compound of formula I can be prepared by reacting gamma-butyrolactone with ethyl formate in the presence of a strong base such as sodium or sodium hydride or sodium alcoholate at -10 to -30 ° C.

Example 1 and d 1

To a suspension of 3.5 g of sodium or 3.6 g of sodium hydride or 10.2 g of sodium ethanolate in 50 ml of diethyl ether, a solution of 13 g of gamma-butyrolactone was added dropwise while stirring at -10 to -30 ° C. 12 g of ethyl formate in 40 ml of diethyl ether. The precipitated (Z) -3- (hydroxymethylene) dihydro-2 (3H) -furanone sodium salt of formula I (95-100%) was either used immediately for reactions or stored without isolation as an ethereal suspension at -30 to -75 ° C. .

Claims (1)

A process for preparing (Z) -3- (hydroxymethylene) dihydro-2 (3H) -furanone sodium salt of formula I, Characterized in that gamma-butyrolactone and ethyl formate are treated with a strong base such as sodium or sodium hydride or sodium alcoholate at temperatures of -10 to -30 ° C.