SYNTHESIS OF [2,2,3-ALPHA,4,4-D5]CP-88,818 (TIQUESIDE), AN INTERNAL STANDARD FOR A QUANTITATIVE HPLC MS ASSAY SYSTEM/

A polydeuterated form of CP-88,818 (1, tiqueside) was needed as an int ernal standard for a quantitative HPLC/MS assay system. [2,2,3alpha,4, 4-D5]CP-88,818 (11) with undetectable D0 content was synthesized in fi ve steps from tigogenin (2). The low D0 content was achieved through t wo sequential incorporation procedures which gave results superior to those achieved through a single incorporation procedure. A preparative ly useful procedure for removing spirostane impurities found in natura lly occurring tigogenin was also discovered.