Specific tritium labeling of cerebrosides at the 3-positions of erythro-sphingosine and threo-sphingosine

Cerebrosides containing either threo- or erythro-[3-3-H]sphingosine were synthesized by a new procedure. Glucopyranosyl or galactopyranosyl ceramides were converted to their 3-keto derivatives with 2,3-dichloro-5,6-dicyanobenzoquinone and reduced with 3-H-labeled sodium borohydride. The resulting tritiated cerebrosides, which contained erythro- and threo-sphingosines in the ratio of 84:16, were deacylated with butanol-KOH, and the erythro- and threo-psychosines were separated by silica gel column chromatography and reacylated with lignoceroyl chloride.