Practical syntheses of [13C]- and [14C]-labelled glucosphingolipids

Synthetic routes to [glucose-U-14C]-1-O-(β-D-glucopyranosyl)-N-stearoyl-D-erythro-sphingosine 1b and to [glucose-13C6]-1-O-(β-D-glucopyranosyl)sphingosine ([glucose-13C6]glucopsychosine, 2b) are described. Whereas the protected ceramide precursor for 1b was prepared using conventional methodology, two new strategies were developed in the course of the synthesis of 2b. Of these, one relies on keeping a protecting group in place at all times to avoid the handling difficulties associated with sphingosine 4, while the other generates a protected derivative (24) of sphingosine indirectly by means of a Mitsunobu inversion.