Highly Stereoselective Aldol-type Reaction of 2-Bromo-2,3,3,3-tetrafluoropropanamide with Aldehydes Leading to erythro-(alpha)-Fluoro-(alpha)-(trifluoromethyl)-(beta)-hydroxy Amides

N-Methoxy-N-methyl-2-bromo-2,3,3,3-tetrafluoropropanamide underwent highly stereoselective aldol-type reaction with various aldehydes under the influence of triphenylphosphine—a catalytic amount of titanium(IV) isopropoxide at room temperature to give the erythro-isomers of (alpha)-fluoro-(alpha)-(trifluoromethyl)-(beta)-hydroxy amides preferentially in good to excellent yields.