DD234674A1 - PROCESS FOR PREPARING SUBSTITUTED 3-ACYL-2H-THIOPYRANESE - Google Patents

Abstract

The invention relates to the field of organic synthetic chemistry and has a method to target, obtained with the substituted 3-acyl-2H-thiopyrans with hydrogen, alkyl, aryl or Hetarylresten in positions 1 to 5 of the ring of readily accessible starting materials can be. The invention has for its object to produce 3-acyl-2H-thiopyrans of the formula III. The object is achieved in accordance with the invention by reacting monothio-b-dicarbonyl compounds of the formula I in which R.sup.1 to R.sup.3 have the same meaning as above, in the presence of a base or as alkali metal or dicyclohexylammonium salts with a, b-ungesettigten carbonyl compounds II, in which R4 and R5 have the same meaning as above, in an organic solvent such as methanol, ethanol, benzene o. The like. At about 20-25C with each other brings the reaction, which precipitates after concentration of the reaction solution in the form of yellow-orange, stable crystals Reaction products III isolated and recrystallized from alcohols. Type III compounds can be used as organic intermediates, in particular for the preparation of polymethine dyes, for the synthesis of pharmaceuticals or pesticides. Formulas I to III

Description

in which R ⁴ and R ^{5 have} the same meaning as above, in an organic solvent such as methanol, ethanol, benzene o. The like. At about 2O-25 ° C to each other brings the reaction, after concentration of the reaction solution in the form of yellow orange, stable crystals precipitating reaction products III

isolated and recrystallized from alcohols.

Field of application of the invention

The invention relates to a process for the preparation of substituted 3-acyl-2H-thio pyran s of the general formula III in which R ¹ , R ² , R ³ , R ⁴ and R ^{s are the} same or different

Hydrogen, alkyl, aryl or Hetarylreste can be. Due to various modification possibilities on the alkyl, aryl and hetaryl radicals, compounds of this type can be used as organic intermediates, in particular for the preparation of polymethine dyes, for the synthesis of pharmaceuticals or pesticides.

Characteristic of the known technical solutions

Substituted 3-acyl-2H-thiopyrans of general formula III in which R ', R ⁴ and R ^{5 are} alkyl and aryl radicals and R ² and R ^{3 are} hydrogen, have hitherto been characterized by [4 + 2] cycloaddition of enaminothioketones with α, / 3-unsaturated carbonyl compounds and subsequent amine elimination (see H.Quiniou, Phosphorus and Sulfur 10 (1981), 1 and other literature cited therein).

The scope of this method is limited by several factors. These include limitations in substituent variation, low yields in the cycloaddition-elimination reaction, and high overhead in the purification of the final products.

Object of the invention

The aim of the invention is to produce substituted 3-acyl-2H-thiopyrans having a broad substituent pattern from readily available starting materials in high purity and with good yields.

Explanation of the essence of the invention

The invention is based on the object, differently substituted 3-acyl-2H-thiopyrans III, the same or different with hydrogen, alkyl, aryl or hetaryl substituted in the positions R ¹ to R ⁵ , to produce.

The object is achieved by reacting a monothio-ß-dicarbonyl I in the presence of a base or as alkali metal or Dicyclohexylammoniumsalze with α, / 3-unsaturated carbonyl compounds II in an organic solvent such as methanol, ethanol or benzene at 20-25 ^c C reacts with each other.

_lBQSa)

I i

From the reaction solution, the substituted 3-acyl-2H-thiopyrans III are isolated immediately or after concentration of the reaction solution in the form of yellow-orange, stable crystals. The products can be purified by recrystallization from methanol or ethanol.

embodiments example 1

Preparation of 3-formyl-5,6-diphenyl-2H-thiopyran

In a solution of 0.8 g (0.02 mol) of sodium hydroxide in 10 ml of water and 0.6 g (0.01 mol) of acrolein in 10 ml of methylene chloride are added with ice cooling 2.4 g (0.01 mol) of a-formyl-ß-mercaptostilbene , The mixture is stirred for three hours at room temperature and heated for one hour at reflux. Then allowed to stand overnight, add 10 ml of water and separates the organic layer. The aqueous phase is extracted with methylene chloride. From the combined organic phases, after drying (Na ₂ SO ₄ ) and concentration, a solid is obtained which is separated off and recrystallized. Yield: 1.9g (66%) m. 148-149 ° C (ethanol)

Example 2

Preparation of 3-acetyl-5,6-diphenyl-2H-thiopyran

4.2 g (0.01 mol) of dicyclohexylammonium salt of the α-formyl-β-mercaptostilbene are suspended in 25 ml of methanol and, while stirring, 0.7 g (0.01 mol) of methyl vinyl ketone are added, whereupon a clear solution is formed. The mixture is stirred for another 30 minutes at room temperature and concentrated in vacuo, whereupon the product crystallizes. It sucks and crystallizes

around. '

Yield: 2.4g (82%)

F. 94-95 ° C (ethanol)

Table 1: Substituted 3-acyl-2H-thiopyrans from monothio-β-dicarbonyl compounds and α, / 3-unsaturated carbonyl compounds

R ¹ R ² R ³ R ⁴ R ⁵ Yield (%) to F to Ex. Ex. 2 ( ⁰ C) 1 86 C ₆ H ₅ C ₆ H ₅ H H H 66 72 148-149 C ₆ H ₅ C ₆ H ₅ H H CH ₃ 48 79 164-165 C ₆ H ₅ C ₆ H ₅ H H C ₆ H ₅ 10 82 83-85 C ₆ H ₅ C ₆ H ₅ H CH ₃ H 21 74 94-95 4-CH ₃ OC ₆ H ₄ 4-CH ₃ OC ₆ H ₄ H H H - 79 138-139 4-CH ₃ OC ₆ H ₄ 4-CH ₃ OC ₆ H ₄ H H CH ₃ - 70 89-90 4-CH ₃ OC ₆ H ₄ 4-CH ₃ OC ₆ H ₄ H H C ₆ H ₆ - 80 141-142 4-CH ₃ OC ₆ H ₄ 4-CH ₃ OC ₆ H ₄ H CH ₃ H - 96-97

CHO

49

70

CHO

135-136

Claims (1)

Erfindungsanspurch: A process for the preparation of substituted 3-acyl-2H-thiopyrans of the formula III in which R ¹ to R ^{5 may be} identical or different, hydrogen, alkyl, aryl or hetar / iridae, characterized in that monothio-β-dicarbonyl compounds of the formula I in which R ¹ to R ^{3 have} the same meaning as above, in the presence of a base or as alkali or dicyclohexylammonium salts mita, / 3-unsaturated carbonyl compounds of the formula II