Synthesis of Phosphatidylcholines Possessing Functionalized Acids at sn -2, and ¹³ C- ¹⁴ N and ¹³ C- ³¹ P Couplings in Their ¹³ C NMR Spectra

Although 4-Me ₂ NC ₅ H ₄ N (DMAP) is a standard base for esterification of (2-Me-6-NO ₂ -C ₆ H ₃ CO) ₂ O (MNBA), N -methylimidazole (NMI) was examined for the condensation of acids with 1-stearoyl-lysophosphatidylcholine because of the non-tailing nature of NMI on silica gel. Acids tested were EPA, α-linolenic acid, TBS ethers of 18-HEPE and ricinoleic acid, acid-labile epoxy acids, and a phenyldiynyl acid. The condensation proceeded well with these acids, and chromatographic separation of resulting phosphatidylcholines and remaining NMI was easily performed. During the characterization of the products by ¹³ C NMR spectroscopy, ¹³ C- ¹⁴ N and ¹³ C- ³¹ P couplings were observed.