METHOD OF PRODUCING 3-(GLYOXYLIDENEMETHYL)-2H-THIOPYRANS Russian patent published in 2024 - IPC C07D335/02 

FIELD: various technological processes.

SUBSTANCE: invention relates to a method of producing 3-(glyoxylidenemethyl)-2H-thiopyrans based on enamin-3-ones, which involves three steps which are carried out without separating intermediate products in one reactor; extraction of the desired products is carried out by filtering the precipitate. At first step, enamine-3-one is thionised with Lawesson's reagent in a non-polar organic solvent at room temperature, in molar ratio enamin-3-one:Lawesson's reagent is from 2:1 to 1:1. At the second step, enamine-3-thione is introduced into a Diels-Alder heteroreaction with acrolein at room temperature with molar ratio of enamine-3-thione:acrolein is from 1:2 to 1:3. At the third step, 2H-thiopyran-3-carbaldehyde is introduced into an aldol-crotonic condensation reaction with methylaryl ketone, for which a solvent is distilled from the reaction mixture at reduced pressure, ethanol and methylaryl ketone are added, the mixture is cooled to -10 °C and sodium hydroxide is added in molar ratio of aldehyde:methylketone:sodium hydroxide is from 1:1:4 to 1:1.2:5. Mixture is mixed while heating to 25 °C. Precipitate of 3-(glyoxylidenemethyl)-2H-thiopyran is filtered.

EFFECT: novel one-pot method of producing 3-(glyoxylidenemethyl)-2H-thiopyrans using readily available and safe reagents, which enables to obtain desired products without isolating intermediate substances and using preparative chromatography.

1 cl, 1 tbl, 1 ex