New optically pure dimethylacetals of glyceraldehydes and their application for lipid and phospholipid synthesis

Article abstract of DOI:10.1016/0009-3084(95)02445-O

A convenient synthesis of new and enantiometrically pure 2-O-protected D-glyceraldehyde dimethylacetals as chiral C-3 building blocks for the synthesis of lipids and phospholipids is described.Benzyl- or allylethers are used as protecting groups in position 2 and 5 of D-mannitol.These intermediates are converted to 2-O-benzyl- or 2-O-alkyl-D-glyceraldehyde dimethylacetals by cleavage with periodic acid in methanol.The two dimethylacetals are useful for the synthesis of mixed chain phospholipids with natural configuration of ester-ester, ester-ether or ether-ether composition.Also, triglycerides with three different alkyl chains, ester of ether, can be prepared.As an example of the varsatility of the new intermediates, we describe the synthesis of 1-O-hexadecyl-2-O-acetyl-sn-glycero-3-phosphocho;ine, the so-called 'platelet activating factor' (PAF), via 1-O-hexadecyl-2-O-benzyl-sn-glycerol. Keywords: Synthetic phospholipids; PAF; Phospholipid analogues; Synthesis; Chiral pool; Glyceraldehyde; C-3 building blocks; Optical purity