The present invention generally relates to muscarinic receptor antagonists, which are useful, among other uses, for the treatment of various diseases of the respiratory, urinary and gastrointestinal systems mediated through muscarinic receptors. The present invention also relates to processes for preparing compounds described herein, pharmaceutical compositions thereof, and methods for treating diseases mediated through muscarinic receptors. Formula (I) or a pharmaceutically accepted salt, pharmaceutically acceptable solvate, enantiomers, diastereomer, polymorph or N-oxide thereof, wherein X is.