Reductive cleavage of potential cholinomimetics thiadiazolidinones: A new family of spiro compounds

The design, synthesis and evaluation of a series of 1,2,4-thiadiazolidinone s with potential muscarinic receptor binding properties has been performed. During the synthesis of the target compounds, we observed an interesting r eductive cleavage of the thiadiazolidinone system which leads to the format ion of the novel piperidine spiro triazine heterocycle. The synthesis, stru ctural elucidation (NMR spectroscopy and X-ray diffraction) and biological evaluation of the new compounds are described. With the structures unequivo cally established, a mechanism for the formation of the spiro compound is p roposed.