Since the identification of platelet activating factor (PAF) as glycero-3-phosphocholine, 1-3 a number of constitutional analogs of PAF have been reported. 4 They have been synthesized for three main purposes: (1) to prove the structural requirements for activity; (2) to enhance the desirable biological activities (e.g., hypotension), while diminishing or eliminating undesirable effects (e.g., platelet aggregation, anaphylaxis); and (3) to discover PAF antagonists.