Compounds of the formulas: ##STR1## wherein Het is an oxazole or oxazine moiety; X is O, S or SO, n is an integer from 3 to 9, Y is an aliphatic bridge; and the various R groups represent hydrogen or various substituents as described herein, are useful as antiviral agents, especially against picornaviruses. N-(Chloroalkyl)amide intermediates for the compounds of Formula I are also active as antiviral agents. Related compounds outside the scope of the above formulas are also disclosed.