A process for the preparation of .alpha.,.beta.-unsaturated carbonyl compounds of the formula I ##STR1## where R.sup.1 is hydrogen, C.sub.1 -C.sub.10 -alkyl, C.sub.1 -C.sub.10 -alkoxy or aryloxy,R.sup.2 is aryl which is unsubstituted or substituted by C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy, trifluoromethyl and/or halogen andR.sup.3 is tetrahydrofuranyl or aryl which is substituted by C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy, trifluoromethyl and/or halogen, which comprises reacting 3-amino-2-propen-1-ones of the formula II ##STR2## where R.sup.1 and R.sup.2 have the abovementioned meanings, and R.sup.4 and R.sup.5 are, independently of one another, hydrogen, C.sub.1 -C.sub.10 -alkyl or aryl, with a magnesium halide of the formula IIIR.sup.3 --Mg--Y (III) where Y is halogen, at from -20.degree. to 100.degree. C., and novel .alpha.,.beta.-unsaturated carbonyl compounds and novel 3-amino-2-propen-1-ones are described.