A Synthesis of d -erythro- and l -threo-Sphingosine and Sphinganine Diastereomers via the Biomimetic Precursor 3-Ketosphinganine

The four stereoisomers of sphingosine and sphinganine can be produced in protected form by a short, convergent, biomimetic synthesis from serine. Yields are good (26−38% overall from commercially available serine derivatives), and the stereoselectivities are excellent (>92% de, >95% ee). Several sphingosine l - threo -sphingosine analogues with modified, functionalized tails were prepared to demonstrate the versatility of the method.