A robust method for preparing (3S)-3-alkyl-3-phenyl-1,4-dioxane-2,5-diones was developed using an improved cyclocondensation reaction between (S)-α-alkylmandelic acids and 2-bromocarbonyl halides. Subtle differences in the reaction conditions, including separate additions of triethylamine, significantly increased the yield compared with Schollkopf's original method.