Novel and convergent synthesis of modified glycosphingolipids, galactosyl-5-aza-sphinganines, by a diversity-oriented method

The stereocontrolled synthesis of β-galactosyl-5-aza-sphinganines was accomplished with high efficiency by a novel and convergent strategy. The truncated β-galactosphinganine 5 was easily acylated with different long chains. Moreover, the simple conversion of thiazole to formyl enabled 5-aza-alkylchains to be introduced via an amino-reduction reaction. The overall yield for the synthesis of β-galacto-5-aza-sphinganines 9 and 13 was about 30-35% starting from 5. Preliminary results concerning the β-transgalactosylation of a truncated sphinganine catalyzed by galactosidases are also presented and discussed.