Regiospecific Opening of Glycidyl Derivatives Mediated by Boron Trifluoride. Asymmetric Synthesis of Ether-Linked Phospholipids

Article abstract of DOI:10.1021/jo00280a034

A short, chiral synthesis of unnatural, cytotoxic ether-linked phospholipids is reported in which the key step is the very high regio- and stereospecific nucleophilic opening of the p-toluenesulfonate (1a, 1b) or tert-butyldiphenylsilyl ether (6a, 6b) derivatives of (R)- or (S)-glycidol with 1-hexadecanol using boron trifluoride etherate as catalyst.The enantiomeric excess of the ring-opened products was >94percent, as judged by 1H NMR and chiral HPLC analysis of the Mosher ester derivatives, indicating that ring opening of 1 and 6 proceeds without significant loss of optical purity.The synthetic strategy of using optically active glycidyl derivatives as the precursor of the glycerol backbone permits the desired enantiomers of 1(3)-O-2-O-methylphosphocholines (5a, 5b) to be generated in good yield and high optical purity from the ring-opened intermediates (2, 7) in three steps without the use of protecting groups.