DD147241A1 - PROCESS FOR THE PREPARATION OF FURANDERIVATES - Google Patents

Abstract

The invention relates to a process for the preparation of furan derivatives. The aim of the invention is to provide a process for the preparation of 3-aryl-5- (fur-2-yl or 5-substituted-fur-2-yl-methylene) -4-oxo-thiazolidin-2-ylidene cyanoacetic acid esters to develop. The furan derivatives of general formula III in which R is an alkyl radical, R & exp1! for an optionally alkoxy-, alkyl- or halogen-substituted phenyl radical or an aryl or hetaryl methyl radical and R & exp2! represent a hydrogen, a halogen atom or a nitro group, can be prepared by reaction of Cyanessigsaeureester the general formula I, in which R and R & exp1! have the above meaning, with 2-furaldehydes of the general formula II in which R & exp2! as defined above. These cyanoacetic acid esters can be used as organic intermediates for further syntheses. They are particularly suitable for the preparation of novel heterocycles.

Description

Yerfahren for the preparation of furan derivatives Application of the invention

The invention relates to a process for the preparation of 3-aryl-5- (fur-2-yl or 5-substituted furls' yl-methylene) -4-oxo-thiazolidin-2-yliden cyanoacetic acid esters.

These cyanoacetic acid esters can be used as organic intermediates for further syntheses. They are particularly suitable for the preparation of novel heterocycles.

Characteristic of the known technical solutions

3-Aryl-5- (fur-2-yl or 5-substituted-fur-2-ylmethylene) -4-oxo-thiazolidin-2-ylidene-cyanoacetic acid esters are not yet known.

Object of the invention

The object of the invention is to provide a process for the preparation of 3-aryl-5- (fur-2-yl or 5-substituted a-2-yl-ethylene) -4-oxo-thiazolidin-2-ylidene- to develop cyanoacetic acid esters.

Explanation of the essence of the invention

The furan derivatives of general formula III in which R is an alkyl radical, R is an optionally alkoxy-, alkyl- or halogen-substituted phenyl group or an aryl or hetaryl methyl group and R 1 is a hydrogen atom.

Substance, a Haiogenatom or a nitro group, can by. Reacting the cyanoacetic acid ester of the general formula I in which R and R have the above meaning, with 2-furaldehydes of the general formula II in which R ^{2 is} as defined above, are prepared.

The reactions are carried out in an aprotic organic solvent, preferably in benzene, toluene or xylene. As a catalyst for the reactions, organic bases, preferably piperidine, are used. The reaction temperatures range from 80 ° to 160 ⁰ C, the reaction times are a function of the reaction temperatures for 30 minutes to 3 hours. After cooling the reaction mixture, the furan derivatives III crystallize out. The yields can be increased by concentrating the mother liquors in vacuo. Purification of the crude products can be carried out by recrystallization from organic solvents.

embodiments Embodiment 1

Ethyl 3- (p-chlorophenyl) -5- (fur-2-ylmethyl) -4-oxo-thiazolidin-2-ylidene cyanoacetate 0.005 mol 3- (p-chlorophenyl) -4-oxo-thiazolidine-2 ethyl-ethylidenylideneactanoate are refluxed with 0.005 mol of 2-furaldehyde and 10 drops of piperidine in 10 ml of xylene for 30 minutes. The mixture is allowed to cool to 20 ⁰ C, filtered and the residue crystallized from glacial acetic acid · yield: 62 # d.Th · m.p .: 298-300 ⁰ C.

Embodiment 2

Ethyl 5- (5-bromo-fur-2-yl-methylene) -3 - * (p-methoxyphenyl) -4-oxothiazolidin-2-ylidene cyanoacetate 0.005 mol 3- (p-methoxyphenyl) -4-oxo ethyl thiazolidin-2-yldenecanoate are mixed with 0.005 mol of 5-bromo-2-

furaldehyde and 10 drops of piperidine in 10 ml toluene for 2 hours under reflux. After cooling to 20 ° C is filtered off and the filtrate concentrated in vacuo. Both residues are recrystallized from glacial acetic acid

Yield: 60% of theory Melting point: 215-217 ⁰ C

Explanatory Note 3

5- (5-Bromo-fur-2-yl-methylene) -3- (fur-2-yl-methyl) -4-oxo-t-hiazolidin-2-ylidene-cyanoacetic acid et hylest he

0.005 mol 3- (fur-2-yl-ethyl) -4-oxo-thlazolidin-2-ylidene-cyanoacetic acid ethyl ester with 0.005 mol of 5-bromo-2-furaldehyde and 2 drops of benzylamine in 10 ml of xyleo for 45 minutes under reflux heated. After cooling to ^{0 0} C is filtered off and the filtrate concentrated in vacuo, both residues are recrystallized from glacial acetic acid

Yield: 81 $ d.Th. Melting point: 175 to 130 ⁰ C

Embodiment 4

Ethyl 5- (fur-2-yl-methylene) -4-oxo-3-phenyl-thiazolidin-2-ylidene cyanoacetate From 0.005 mole of 4-oxo-3-phenyl-thiazolidin-2-ylidenoyanoacetic acid ethyl ester and 0.005 mole 2-Furaldehyde, as described in Example 1. Yield: 68% of theory Melting point: 263-265 ⁰ C

Embodiment 5

Ethyl 5- (Fur-2-yl-methylene) -3- (p-methoxyphenyl) -4-oxo-thiazolidin-2-ylidene cyanoacetate From 0.005 mol of 3- (p-methoxyphenyl) -4-oxo-thiazolidine Ethyl 2-ylidene cyanoacetate and 0.005 mol of 2-furaldehyde as described in Example 2. Yield: 77% of theory Melting point: from 310 ^° C.

decomposition

Claims (2)

A process for the preparation of furan derivatives of the general formula III in which R is an alkyl radical, R is an optionally alkoxy-, alkyl- or halogen-substituted phenyl radical or an aryl or hydrogen radical. aryl-methyl radical and R stand for a hydrogen, a halogen atom or a nitro group, characterized in that cyanoacetic acid ester of the general formula I in which R and R have the above meaning, with 2-furaldehydes of the general formula II in which R as defined above, be implemented » For this .... // ... pages formulas