METHOD FOR OBTAINING DERIVATIVES OF 3,4-DIHYDRO-2H-THIOPYRAN Russian patent published in 2018 - IPC C07D335/02 C07D335/04 C07D409/04 

FIELD: technological processes.

SUBSTANCE: invention relates to the preparation of 3,4-dihydro-2H-thiopyran derivatives, that can potentially be used as monomers, intermediates in the synthesis of biologically active substances, fragrances and other practically meaningful compounds. Process for the preparation of 3,4-dihydro-2H-thiopyran derivatives from α,β-unsaturated ketones and dienophiles are carried out by Diels-Alder hetero-reaction at an elevated temperature, at atmospheric pressure in a dried aprotic non-polar solvent using the Lawesson's reagent as a sulfurizing agent, followed by isolation of the desired products, where the process is carried out in one stage at a temperature of 60 to 90 °C for 4–12 hours at a molar ratio α,β-Unsaturated ketone: Lawesson's reagent: dienophile from 1:0.5:0.9 to 1:1.2:1.2; with the subsequent isolation of the desired products by cooling the resulting mixture, filtering off the precipitate, recrystallization from the polar protic solvent, either by distilling off the solvent under reduced pressure, triturating the residue with a minimum amount of diethyl ether until crystallization, filtering off the precipitate, further purification by flash chromatography using dried methylene chloride as the eluent, or distilling off the solvent under reduced pressure, dissolving the precipitate in diethyl ether, cooling the resulting mixture to crystallization, and filtering off the precipitate.

EFFECT: result of the invention is a novel simple process for the preparation of 3,4-dihydro-2H-thiopyran derivatives, which does not require the purification of products by column chromatography, a large solvent consumption, and provides a good yield of the product.

1 cl, 2 tbl, 6 ex