Structural elucidation and synthesis of doping-relevant SARM- and SERM-metabolites

Abstract

New achievements in pharmaceutical research constantly extend the range of doping-relevant substances. Efficient combating of illegal drug abuse in high-performance sports affords profound knowledge of drug metabolism. This is often aggravated by the fact that many substances, though already freely available on the black market, in fact are still objects of clinical trials and not even approved for the clinical administration on patients. The following research deals with the structural elucidation and synthesis of metabolites of different doping reagents, which are needed as reference substances for doping analysis. An efficient synthetic route was developed, that facilitates the synthesis of two important arylpropionamide-based SARM metabolites. Via epoxidation, amide bond formation and epoxide opening these metabolic products of andarine and ostarine can be obtained in their racemic forms and with slight modifications also in enantiopure form. Comparison to excretion studies confirmed their utility as reference substances for the detection of SARMs abuse. Different approaches for the synthesis of 4--hydroxyclomiphene, a potential metabolite of the SERM clomiphene, are presented. Whereas the application of a McMurry coupling reaction and a Horner Wadsworth Emmons reaction turned out to be not expedient, stannyl lithiation of an acetylenic precursor compound followed by a Negishi coupling reaction finally gave the target metabolite. As this structure was shown not to be applicable for doping control purposes, a synthetic approach towards 3,4-di-hydroxy-di-hydroclomiphene featuring two consecutive Pd-catalyzed --arylation steps was compiled. Additionally a model system for the simulation of clomiphene-s metabolism applying human liver microsomes was developed. It facilitated the preparation of a larger quantity of major metabolic products that were analyzed by LC-SPE-NMR/MS. The obtained 1H-NMR spectra have shown that 4-hydroxyclomiphene is a useful reference substance for LC-MS-based doping tests.