The present invention relates to compounds of formula I: ##STR00001## or pharmaceutically acceptable acid addition salts thereof, where;R.sup.1 is C.sub.1-C.sub.6 alkyl, substituted C.sub.1-C.sub.6 alkyl, C.sub.3-C.sub.7 cycloalkyl, substituted C.sub.3-C.sub.7 cycloalkyl, C.sub.3-C.sub.7 cycloalkyl-C.sub.1-C.sub.3 alkyl, substituted C.sub.3-C.sub.7 cycloalkyl-C.sub.1-C.sub.3 alkyl, phenyl, substituted phenyl, heterocycle, or substituted heterocycle;R.sup.2 is hydrogen, C.sub.1-C.sub.3 alkyl, C.sub.3-C.sub.6 cycloalkyl-C.sub.1-C.sub.3 alkyl, or a group of formula II ##STR00002## R.sup.3 is hydrogen or C.sub.1-C.sub.3 alkyl;R.sup.4 is hydrogen, halo, or C.sub.1-C.sub.3 alkyl;R.sup.5 is hydrogen or C.sub.1-C.sub.3 alkyl;R.sup.6 is hydrogen or C.sub.1-C.sub.6 alkyl; andn is an integer from 1 to 6 inclusively.The compounds of the present invention are useful for activating 5-HT.sub.1F receptors, inhibiting neuronal protein extravasation, and for the treatment or prevention of migraine in a mammal. The present invention also relates to a process for the synthesis of intermediates in the synthesis of compounds of Formula I.