An asymmetric synthesis of (R) and (S)-1-alkoxy-2,3-propanediols including precursors to platelet activating factor.

The titanium-assisted nucleophilic opening of glycidol with primary aliphatic alcohols gives 1-alkoxy-2,3-propanediols. The titanium alkoxide used in the reaction should be the alkoxide of the alcohol used for the reaction. When optically active (S)-glycidol is used in the reaction, (S)-1-alkoxy-2,3-propanediols are obtained without loss of optical activity. When the reaction is carried out at 70-75 degrees C without solvent, the 1-alkoxy-2,3-propanediols are obtained in yields of 45-59%. The regioisomeric 2-alkoxy-1,3-propanediols are found to the extent of 4-6% in the reaction. The optical purity of glycidol can be measured from the high field (500 MHz) nuclear magnetic resonance spectrum of the Mosher ester.