The preferential hydrolysis of a G2PX over a G3PX could have occurred in any alkaline body of water, and the selection of any natural glycerophospholipid headgroup (G3PX) could have originated from its greater hydrolytic stability relative to that of its non-natural analogue (G2PX). Prebiotic synthesis of complex lysophospholipids. Cyclic lysophosphatidic acids, considered as precursors to complex phospholipids, have been proposed as components of primitive membranes due to their stability to a broad range of pH values and divalent metal ions. Bolstered by the findings described above, we wondered if cyclic lysophosphatidic acids could be converted into lysophosphatidylethanolamines (10:0 lyso GPEs), lysophosphatidylcholines (10:0 lyso GPCs), and lysophosphatidylserines (10:0 lyso GPSs), all known substrates for the non-enzymatic synthesis of diacyl glycerophospholipids. We thus investigated the ring-opening of 1-decanoyl glycerol-2,3-cyclic phosphate (10:0 lyso G>P) with 2-amino alcohols, starting with the reaction of EA. In aqueous medium at pH 9.5, ester hydrolysis predominated over ring-opening, but traces (<1%) of 10:0 lyso GPEs were formed after 24 h ( 31 P-NMR; Fig. and). To minimize ester hydrolysis, the same process was performed in the dry state: 10:0 lyso G>P and EA were dissolved at pH 9.5, and the solvent was allowed to evaporate at room temperature in an open Petri dish. The dried mixture was heated at 60°C for 24 hours and dissolved in 0.1 M Triton X-100 in H2O:D2O (9:1, v/v) to preclude the formation of any supramolecular aggregates that would hinder analysis by NMR. Formation of 10:0 lyso GPEs was indicated by a pair of peaks at 0.05 ppm (10:0 lyso G3PE, 14%) and -0.74 ppm (10:0 lyso G2PE, 10%), alongside their ester-hydrolyzed derivatives G3PE and G2PE (25% cumulative yield) ( 31 P-NMR; Fig. and). Spectroscopic ( 1 H-coupled 31 P-NMR) studies, spiking experiments, and LC-MS analyses supported these assignments. Yields of 10:0 lyso GPEs increased with temperature (Fig. ), and only traces of lysophosphatidic acids were detected. Notably, independent of the heating temperature, the natural regioisomer 10:0 lyso G3PE was generated preferentially (Fig. ). By comparison, the reaction of G>P with EA in the dry state (24 hours, 60°C) gave a mixture of GPEs and GPs in 49% and 6% cumulative yields, respectively (Fig. ). When the transformation of 10:0 lyso G>P was repeated in the presence of MEA, DEA, and Ch, the corresponding lysophospholipids were detected by 31 P-NMR and LC-MS (Fig. ). Nonetheless, when 10:0 lyso G>P was reacted with Ser, 10:0 lyso GPSs were not observed (Fig. ).