A short synthesis of rigid 2-alkylthio-2,2-diaryl substituted acetic acids

The metalation of rigid di-Ph methane derivs., e.g., thioxanthene, has been studied, aiming at the synthesis of 2-alkylthio-2,2-diaryl substituted acetic acid esters, a class of compds. with a potential antimuscarinic activity. Mixed metal bases have shown to be necessary in order to obtain the desired compds. with a good regiocontrol.