The invention relates to a method of preparing compounds of the formulaand to pharmaceutically acceptable salts thereof. The compounds of formula 1 are antibacterial agents that may be used to treat various bacterial and protozoa infections. The invention also relates to pharmaceutical compositions containing the compounds of formula 1 and to methods of treating bacterial protozoa infections by administering the compounds of formula 1. The invention also relates to methods of preparing the compounds of formula 1 and to intermediates useful in such preparation.