YL-N-3-[4-(3-METHYLPHENYLAMINO)-3-PYRIDYLSULFONYL] GUANIDINE

The title compound, C17H20N6O2S, is a bioisoster of torasemide, a loop diuretic whose structure has been described previously. The sulfonylu rea chain of torasemide is replaced by a sulfonylcyanoguanidine functi on. Whereas the torasemide molecule and some sulfonylurea derivatives exhibit one of the three alpha, beta or gamma conformations, the confo rmation being assigned according to the torsion angles in the side cha in, the title compound displays a new delta conformation. This conform ation is stabilized by two intramolecular N-H ... O hydrogen bonds. A prototropic form of the title compound corresponding to it zwitterion [-S-N--C-, N+-H (pyridinium)] is observed {i.e ylphenylamino)-3-pyridi niosulfonyl]guanidin-3-ide} . The crystal cohesion is the result of bo th van der Waals interactions and one intermolecular N+-H ... N- hydro gen bond involving the N atoms of the zwitterion,