anti-Diols from α-Oxyaldehydes: Synthesis and Stereochemical Assignment of Oxylipins from Dracontium loretense

Differentially protected 1,2-diols were synthesized by enantioselective aldehyde alpha-oxygenation followed by organo-magnesium or -lithium addition. Contrary to a previous report, the resultant diols possess an anti configuration. Good selectivity was achieved regardless of the hybridization state of the nucleophile or the presence or absence of branching. This method was applied to short syntheses of all possible stereoisomers of two oxylipins from Dracontium loretense with incomplete stereochemical assignments. Spectroscopic comparisons between the synthetic and natural oxylipins led to unambiguous assignments.