DD275679A1 - PROCESS FOR PREPARING SUBSTITUTED 5- (2-AMINO-THIAZOL-5-YL) PENTA-2,4-DIEN-1-ONE - Google Patents

Abstract

The invention relates to a process for the preparation of substituted 5- (2-amino-thiazol-5-yl) -penta-2,4-dien-1-ones and relates to the field of organic synthetic chemistry. It has a method for the target, with which substituted 5- (2-amino-thiazol-5-yl) -penta-2,4-dien-1-one of the general formula III, in which R1-R4 aryl radicals and R5 and R6 are alkyl radicals, can be prepared from readily available starting materials in a one-step process. Type III compounds can be used as organic intermediates or dyes. The invention has for its object to produce the title compounds from suitably substituted Pyryliumsalzen. The object is achieved according to the invention by using pyrylium salts of the formula I in which R.sup.1, R.sup.2 and R.sup.3 are aryl radicals and X is an arbitrary anion, with 2-amino-thiazoles of the formula II in which R.sup.4 is an aryl radical and R.sup.5 and R.sup.6 are identical, different or linked together alkyl radicals, in the presence of a buffer component which may be an alkali metal or dialkylamine salt of a weak acid, in solvents such as lower alcohols, halogenated hydrocarbons or dipolar aprotic solvents and thereby applies temperatures up to the boiling point of the reaction mixture.

Description

be generated. The dialkylamine of the amine salt need not be mixed with the AmIn, which is the dialkylamino radical in the 2-position of the

Thiazole Il is based on being identical. The reaction products III differ when working with alcohols or acetonitrile as solvent) usually directly from

the reaction mixture in crystalline form, so that their isolation is possible without difficulty (variant A, see.

Exemplary Embodiment 1) When using halohydrocarbons as reaction mods, the reaction mixture is added

resulting reaction mixture with water and the products III isolated by concentration of the organic phase (variant B,

Embodiment 2). Crude adherent traces of unreacted Pyrvliumsalzes are advantageous by hydrolysis using triethylamine / Removed water during recrystallization. The invention is explained below with reference to two exemplary embodiments in the form of general working instructions. embodiments example 1 Substituted 5- (2-amino-thiazol-5-yl) -penta-2,4-dien-1-ones III by reaction of pyrylium salts I with aminothiazoles II in

lower alcohols or dipolar aprotic solvents (general procedure, variant A, see Table 1)

It is heated 5 mmol of pyrylium I (X = CIO ₄ ), 7.5 mmol 2- / minothiazol II and 5 mmol buffer component in 10 ml of the respective Solvent 5h. under reflux. The precipitated when cooling the reaction mixture raw products

filtered off and recrystallized from acetone / ethanol with the addition of a few drops of triethylamine and 2 ml of water.

Example 2 Substituted 5- (2-amino-thiazol-5-yl) -penta-2,4-diene-1-ones ||| by reaction of pyrylium salts I with aminothiazoles II in Halogenated hydrocarbons (general procedure, variant B, see Table 1)

5 mmol Pyrviiumsalz I (X = CIO ₄ ), 7.5 mmol of 2-amino-thiazole II and 5mmol buffer component are dissolved in 1OmI

Halogenated hydrocarbon heated for 5 hrs. Reflux. After cooling, the reaction mixture is treated with water, the

abkotrennt the organic phase and the aqueous phase extracted twice with the halogenated hydrocarbon used for the reaction. After washing twice the organic :! Solutions with water are dried over sodium sulphate, pulling this

Solvent i. Vak. and brings the remaining residue by treatment with ethanol for crystallization. The cleaning

takes place analogously to embodiment 1.

Yields and melting points of the 5- (2-aminothiazol-5-yl) -penta-2,4-dien-1-ones prepared according to the working examples

Verb. R ¹ R ² R ³ 4-Me-CJH < R ⁴ NR ⁶ R ^e buffer solution Au sb. 53 Mp. 4-CI-CjH ₄ component medium (%) " 58 ( "C) IIIa Ph Ph Ph 4-Br-CjH ₄ Ph piperidino Piperfdinacetat ethanol 81 78 184-186 Ph Piperidine acetate ²¹ ethanol 72 76 Ph Piperidinpro- ethanol 77 89 propionate " 59 Ph Piperidinben- ethanol 64 90 Ph zoai dimethylamine ethanol 58 85 Ph acetate 88 sodium 'Ethanol 65 64 Piporidinacetat n-propanol 65 piperidine acetonitrile 60 57 * piperidine Mothylen- 36 60 chloride 85 piperidine Chloroform 25 IIIb Ph Ph Ph Ph pyrrolidino pyrrolidineacetate ethanol 192 to 193.5 IIIc Ph 4-Me-C ₆ H ₄ Ph Ph piperidino piperidine ethanol 183-185 IIId Ph 4-CI-CjH ₄ Ph Ph piperidino piperidine ethanol 194-196 IIIe Ph 4-Br-C ₆ H ₄ Ph Ph piperidino piperidine ethanol 192-194 HIF Ph 4-O ₂ N-CjH ₄ Ph Ph piperidino piperidine • ethanol 221-223 HIg 4-Me-C ₈ H ₄ Ph Ph piperidino piperidine ethanol 178-180 IHH 4-CI-C _e H ₄ Ph Ph piperidino piperidine ethanol 160-162 Uli 4-Br-C »H ₄ Ph Ph piperidino piperidine ethanol 201-203 Hij Ph Ph 4-Me-C ₈ H ₄ piperidino piperidine ethanol 196-198 HIK Ph Ph 4-Me-CjH ₄ dimethyl Dimetttylamin- ethanol 182-184 amlno acetate HII Ph Ph. 4-Et-CjH ₄ piperidino Piperidinacetet ethanol 165-167 JIIm Ph Ph 4-CI-CjH ₄ piperidino piperidine ; ethanol 159-160 down Ph Ph 4-Br-CjH ₄ piperidino piperidine ^; ethanol 170-171

1 The yields refer to the crude products;

2 Produced by combining squtmolar amounts of amine and acid directly in the reticule plate.

FomolMlt "

Buffer component -HX

NR ⁵ R ⁶

Claims (2)

1. A process for preparing substituted 5- (2-amino-thiazol-5-yl) -penta-2 _/ 4-dien-1-ones of the formula III in which FO-R ^{4 is} aryl radicals and R ⁵ and R ^{e are} identical, represent different or mutually linked Alkvireste, characterized in that pyrylium salts of the formula I in which R ¹ , R ² and R ³ aryl radicals and X is an arbitrary anion, with 2-amino-thiazoles of the formula II, in the R ⁴ a Aryl and R ⁶ and R ^{e have} the abovementioned meaning, in the presence of a buffer component in solvents such as lower alcohols, for. For example, ethanol or n-propanol, halogenated hydrocarbons, eg. As methylene chloride or chloroform, or dipolaraprotic Solvenzen, z. As acetonitrile, and while applying temperatures up to the boiling point of the reaction mixture. 2. The method according to item 1, characterized in that the buffer component alkali metal salts of weak acids, eg. For example, sodium acetate, or dialkylamine weak acids, eg. For example, the acetates, propionates or benzoates of piperidines or dimethylamines (either used in substance or produced by combining equimolar amounts of dialkylamine and acid in the reaction mixture) can be used. For this 1 page formulas Field of application of the invention The invention relates to a process for the preparation of substituted 5- (2-aminothiazol-5-yl) -penta-2,4-dien-1 -ones of general formula III in which R ¹ , R ² , R ³ and R ⁴ aryl radicals and R ⁶ and R * Ajkylreste mean. Compounds of this type of structure can be used as organic intermediates due to the possibility of modification of the aryl radicals, the pantadienone structure and the Thiazolsyst6m as dyes and because of their absorption in the visible spectral range as dyes. Characteristic of the known technical solutions Substituted 6- (2-aminothiazol-5-yl) -penta-2,4-dien-1 -ones of the general formula III in which R ¹ - R * have the abovementioned meaning are not known ( See: RHWILEY, DCENGLAND and LCBEHR, Org. Reactions β [1951] 376; JM SPRAGUE and AH LAND; in: Heterocyclic Compounds (edited by RC ELDERFIELD), Vol.5, New York: John Wiley and Sons, Inc., London: Chapman and Hill, Limited, 1957, p.484; The Chemistry of Heterocyclic Compounds, Vol. 34, Part 1-3, Thiazoles and its Derivatives (Ed. JV METZGERJ, New York, Chl. Ch., Brisbane, Toronto: 1979; F. KURZER: in: Organic Compounds of Sulfur, Selenium and Tellurium [Published by DHREID], London: The Chemical Society, Vol. 1 [1970], p.378; Vol.2 [1973], p.587; 3 [1975], p.566; B.IDDON and PALOWF, ibid., Vol.4 [1977], p.356; vol.5 [1979], p.358; M. Davis, ibid., Dd.6 [1981 J. METZGER: in: Comprehensive Heterocyclic Chemistry [Ed. AR KATRITZKY, CW REES], Oxford, New York, Toronto, Sydney, Paris, Frankfurt: Pergamon Press 1984, Bd 235; Chem. Abstr. Vol. 1 [1907] - Vol. 108 [1988] Issue 24). About the potential possibility compounds of type III, for example by cyclization of suitably substituted Pentadienone to Pentedienonyl-thlazoles by standard methods of thiazole, by stepwise construction of the Pentadienonylseitenkette represent (starting from appropriately functionalized Thiazolderviaten) or by reacting electrophilor agents with 2-dialkylamino-thiazoles, are none Information ahead. However, these synthetic variants would be linked to the presence of specially substituted starting materials, the production of which is usually associated with a considerable preparation effort. Object of the invention The aim of the invention is to produce from readily available starting materials in a one-step process 5- (2-aminothiazol-5-yl) -penta-2,4-dlen-1-one, which in 1-, 3- and 5 Position of the penta-2,4-dien-1-one chain and in the 4-position of the thiazole ring carry aryl radicals and on the amine nitrogen atom alkyl radicals. Explanation of the essence of the invention The invention has for its object to use for preparing the title compounds suitably substituted pyrylium salts. The object is achieved in that pyrylium salts of the formula I, In the R ¹ , R ² and R ³ aryl radicals and X is an arbitrary anion, with 2-amino-thiazoles of the formula II in which R ^{4 is} an aryl radical and R * and R * gloiche, represent different or interlinked alkyl radicals, in Gagenwart a buffer component and thereby reacting as a solvent lower alcohols, eg. For example, ethanol or n-propanol, halogenated hydrocarbons, eg. Methylene chloride or chloroform, or dipolar aprotic solvents, e.g. As acetonitrile, used and applies temperatures up to the boiling point of the reaction mixture. Suitable buffer components are alkali metal salts of weak acids, eg. For example, sodium acetate or DialkylaMlnealze weak acids such as the acetates, propionates or benzoates of piperidines and dimethylamines. The latter can be used in bulk or directly in the reaction mixture by combining equimolar amounts of amine and acid