A new route to racemic erythro-sphingosine and ceramides. The 1,2-versus 1,4-addition reaction of hexadec-2-enal with 2-nitroethanol

Abstract

The reaction of hexadec-2-enal (5) with 2-nitroethanol (3) in triethylamine gave the 1,2-adducts (8) and (9), while the reaction in methanol–potassium carbonate gave the Michael adducts (6) and (7). Epimerization of the threo-acetonide (10) smoothly gave the erythro-acetonide (11), which gave the amino acetonide (12) on reduction. Phthaloylation, deacetalization, and deprotection of compound (12) gave rac-erythro-sphingosine (1). On the other hand, acylation and deacetalization of compound (12) gave the ceramide (16).