Isolation and identification of impurities in L-696, 229 drug substance

Two low level impurities in 3-[2-(2-benzoxazolyl)ethyl]-5-ethyl-6-methyl-2(1H)-pyridinone drug substance (L-696,229) have been isolated by a combination of preparative HPLC, solid-phase extraction and liquid—liquid extraction. They were identified as 3-[2-(2-benzoxazolyl)ethyl]-5-ethyl-6-(2-phenylethyl)-2(1H)-pyridinone (I) and 6,6′-(2-phenyl-1,3-propanediyl)bis[3-[2-(2-benzoxazolyl)ethyl]-5-ethyl-2(1H)-pyridinone] (II) by mass spectrometry and by their 13 C and 1 H-NMR spectra.