Novel compounds of the formula: ##STR1## wherein R and R.sup.1 are C.sub.1 -C.sub.6 alkyl or cycloalkyl and R.sup.2 and R.sup.3 are independently selected from C.sub.1 -C.sub.6 alkyl or aryl or --NR.sup.2 R.sup.3 forms a heterocyclic group which may be further substituted are disclosed. These compounds were found to possess muscle relaxant properties.