Reaction of trifluoromethyl 1,3-dicarbonyl compounds with formaldehyde and esters of natural α-aminoacids

Condensation of fluorinated 1,3-dicarbonyl compounds with formaldehyde and I-amino acid ester hydrochlorides in acetate buffer, AcONa AcOH (pH 5.9), at room temperature gave chiral hexahydropyrimidines, both containing and lacking a trifluoroacetyl group at position 5 of the heterocycle. In contrast, the reaction of ethyl 3-oxo-4,4,4-trifluorobutanoate with formaldehyde and ethyl (S)-tyrosinate hydrochloride under the same conditions gave a new chiral tetrahydropyrimidinium salt containing the trifluoroacetate anion in good yield. It is interesting that one of the formaldehyde molecules acts as an oxidant in this process. [GRAPHICS] .