A Concise and Scalable Synthesis of High Enantiopurity (−)- d -erythro-Sphingosine Using Peptidyl Thiol Ester−Boronic Acid Cross-Coupling

A short and efficient synthesis of high enantiopurity (-)-D-erythro-sphingosine has been achieved in 71% yield over 6 steps from N-Boc-L-serine. The key steps are high yield, racemization-free, palladium-catalyzed, copper(I)-mediated coupling of the thiophenyl ester of N-Boc-O-TBS L-serine with E-1-pentadecenyl boronic acid and the highly diastereoselective reduction of the resulting peptidyl ketone with LiAl(O-t-Bu)3H. By using this concise route (-)-D-erythro-sphingosine can be prepared on large scale and in high enantio- and diastereopurity (ee >99%, de up to 99%).