Compounds of the formula ##STR1## wherein R.sup.1 and R.sup.2 are independently benzyl substituted benzyl, phenyl or substituted phenyl, said substituted benzyl and substituted phenyl substituted on the phenyl ring with one or more substituents independently selected from the group consisting of halo, lower alkyl and trifluoromethyl; X and Y are independently oxygen or sulfur with the proviso that Y is not oxygen when R.sup.2 is phenyl or substituted phenyl; and the antimicrobial acid addition salts thereof are useful as antifungal, antibacterial and antiprotozoal agents.