Molecular modulation of muscarinic antagonists. Synthesis and pharmacological profile of 2,2-diphenyl-2-ethylthioacetic and 3,3-diphenyl-3-ethylthiopropionic acid derivatives characterized by a dipeptide spacer.

The synthesis and preliminary pharmacological profile of a new series of muscarinic antagonists, derived from previously studied 2,2-diphenyl-2- ethylthio-acetic acid esters, are reported. The parent molecules were decorated with linkers of different length, carrying an amino group to catch a putative anionic function outside the recognition site of the receptor. It was hoped that the interception of this function would give molecules with higher potency and selectivity. The attempt has not been successful, but a new series of compounds with a peculiar pharmacological profile has been identified.