CS238929B1 - Process for preparing (Z) -3- (hydroxymethylene) -5-methyl-dihydro-2 (3H) -furanone sodium salt - Google Patents

Abstract

Method for preparing the sodium salt of /Z/-3-/hydroxymethylene/-5-methyldihydro-2/3H/-furanone of formula I, h I This salt is prepared according to the invention by treating γ-α-valerolactone and ethyl formate with metallic sodium or sodium hydride or sodium alcoholate at low temperatures. The sodium salt of /Z/-3-/hydroxymethylene/-5- -methyldihydro-2/3H/-furanone is a reactive nucleophilic agent, allowing the preparation of pure derivatives of /Z/-3-/hydroxymethylene/-5- -methyldihydro-2/3H/-furanone.

Description

The present invention relates to a process for the preparation of the (Z) -3- (hydroxymethylene) -5-methyldihydro-2 (3H) -furanone sodium salt.

3- (hydroxymethylene) -5-methyldihydro-2 (3H) -furanone sodium salt, first prepared without isolation in 1959 (Korte, F., Buchel, H., Scharf, D., Zschocke, A .: Chem. Ber. 92, 884 (1959) and first isolated in 1977 (Vaidya, A.R., Gogce, N.N., Tilak, B. D., Indian J. Chem. 15B, 403 (1977)], is a reactive nucleophilic agent.

It was found / Mazal C., Rothová V., Jonas J .: Coll. Czech. Chem. Commun./ that, according to the literature, the prepared sodium salt of 3- (hydroxymethylene) -5-methyldihydro-2 (3H) -furanone is a mixture of (E) - and (Z) -isomers whose ratio depends on the method of preparation, length and temperature storage and moisture content is therefore a function of the sample history.

Both isomers were characterized by physicochemical data and reactions with sulfonic and carboxylic acid halides.

A simple process for the preparation of the (Z) -isomer of the sodium salt of 3- (hydroxymethylene) -5-methyldihydro-2 (3H) -furanone of formula I has now been found,

H h ₃ c

ONe

-O (1), which allows only one geometric isomer to be used in the reactions and thus allows the preparation of pure (Z) -3- (hydroxymethylene) -5-methyldihydro-2 (3H) -furanone derivatives. The compound of formula I is prepared by reacting to gamma-valerolactone of formula II

H ₃ C

O (11) and ethyl formate are generally selected from sodium or sodium hydride or sodium alcoholate at a gamma-valerolactone: ethyl formate: base molar ratio of 1: 1 to 2: 1 at -10 to -30 ° C.

Example

To a suspension of 1 g of sodium in 30 ml of diethyl ether was added 0.1 ml of ethanol, and then, while stirring and cooling to -15 to -25 ° C, a solution of 4.5 g of gamma-valerolactone and 3.5 g of ethyl formate in 25 ml was added dropwise. ml of diethyl ether for 5 hours.

The resulting suspension of sodium / Z / -3 / hydroxymethylene / -5-methyldihydro-2 / 3H / -furanone of the formula I / 75% / £ infrared spectrum nu Jolu: strong bands at 777 and 790 cm ^-1 J was used immediately BU3 to reactions or stored at -30 ° C.

Claims (1)

SUBJECT OF THE INVENTION Process for the preparation of the (Z) -3- (hydroxymethylene) -5-methyldihydro-2 (3H) -furanone sodium salt of the formula I H, characterized in that the gamma-valerolactone of the formula XI is used H-iC -O = < (11) and the ethyl formate is generally selected from sodium or sodium hydride or sodium alcoholate at a gamma-valerolactone: ethyl formate:: base molar ratio of 1: 1 to 2: 1 at -10 to -30 ° C.