Obscuraminols, new unsaturated amino alcohols from the tunicate Pseudodistoma obscurum: structure and absolute configuration

The study of the ascidian Pseudodistoma obscurum from Tarifa Island (Cádiz, Spain) has led to the characterization of six new unsaturated 2-amino-3-ol compounds, the obscuraminols A-F. Five of them, the obscuraminols B–F, were isolated as their corresponding diacetyl derivatives. Their structures were established by spectroscopic analysis, their relative configurations by NOEDS study of oxazolidinone derivatives, and their absolute configurations by application of Mosherʹs method to N-acetyl derivatives.