Competitive ways for three-component cyclization of polyfluoroalkyl-3-oxo esters, methyl ketones and amino alcohols

The competitive routes were found for three-component cyclization of polyfluoroalkyl-3-oxo esters, methyl ketones with 3-amino alcohols. It was shown that the reactions with 3-aminopropanol in 1,4-dioxane predominantly lead to hexahydropyrido[2,1-b][1,3]oxazin-6-ones, and in ethanol to 3-hydroxypropylaminocyclohexenones. In contrast, cyclizations with 2-aminoethanol and its analogues, regardless of the reaction conditions, yield hexahydrooxazolo[3,2-a]pyridin-5-ones as the main products. The trans- and cis-diastereomeric structure of heterocycles was established using X-ray and 1H, 19F, 13C NMR spectroscopy, 2D 1H-13C HSQC and HMBC experiments. The mechanism is proposed for competitive transformations of polyfluoroalkyl-3-oxo esters, methyl ketones with 3-amino alcohols.