PROCESS FOR THE PREPARATION OF 1-(4-TETRAHYDROPYRANYL) OR 1-(4-TETRAHYDROTHIOPYRANYL)-PROP-1-EN-3-ONES

Process for the preparation of 1-(4-tetrahydropyranyl)- or 1-(4-tetrahydrothiopyranyl)prop-1-en-3-ones of the general formula I in which R denotes hydrogen, C1- to C10- alkyl, C1- to C10-alkoxy or aryloxy, R denotes hydrogen, C1- to C4-alkyl or aryl optionally substituted by C1- to C4-alkyl and/or halogen and X denotes oxygen or sulphur by reacting 1-aminoprop-1-en-3-ones of the general Formula II in which R and R have the abovementioned meanings, and R and R independently of one another denote hydrogen, C1- to C4-alkyl or aryl, or jointly denote a C2- to C7-alkylene chain, with a 4-tetrahydropyranyl- or 4-tetrahydrothiopyranyl magnesium halide of the general Formula III in which X has the abovementioned meanings and y represents halogen, at temperatures from (-20) to 100 DEG C, and novel 1-(4-tetrahydropyranyl)- or 1-(4-tetrahydrothiopyranyl)prop-1-en-3-ones.