Use of heterocycles as chiral ligands and auxiliaries in asymmetric syntheses of sphingosine, sphingofungins B and F

D-erythro-Sphingosine and its derivatives (dihydrosphingosine, cis-sphingosine, etc.), sphingofungins B and F have been synthesized from simple achiral compounds using heterocyclic compounds as key chiral ligands and auxiliaries. 5- Benzyloxy-4-ethynyl-2,2-dimethyl-1,3-dioxane (5 or 5-ent), a key intermediate for the synthesis of sphingosine family was prepared from 1-trimethylsilylpropinal and ketene silyl acetal 4 using a Sn(OTf)(2)-chiral ligand 1 or 1-ent-catalyzed asymmetric aldol reaction. Sphingosine and its derivatives were readily prepared from 5 according to standard transformation. The chiral hydrophobic side chain (6) of sphingofungin B was synthesized using a catalytic asymmetric aldol reaction using chiral ligand 1-ent. Another key step in the total synthesis of sphingofungin B was a condensation of chiral aldehyde 7 and chiral heterocycle 2. Similarly, the reaction of chiral aldehyde 8 with heterocycle 3 was a key step for the synthesis of sphingofungin F. Highly diastereoselective reactions proceeded smoothly in both cases to afford the corresponding adducts in high yields. (C) 1998 Elsevier Science Ltd. All rights reserved.