A method for the production of a-O-galactosyl ceramide precursor is demonstrated. The method involves the reaction of galactosyl iodide with a sphingosine derivative or phytosphingosine derivative in the presence of a quaternary ammonium iodide salt to prepare the a-O-galactosyl ceramide precursor in the a-anomer form. The a-O-galactosyl ceramide is then prepared by reaction with a suitable fatty acid or fatty acid derivative.