A compound of the formula ##STR1## wherein R.sub.1 is phenyl substituted with 1 to 3 lower alkoxy groups, or 1 to 3 halogens; R.sub.2 is hydroxy or lower alkanoyloxy; R.sub.3 and R.sub.4 are each independently lower alkyl or together form a pyrrolidine or piperidine ring; and n is 2 to 4, and pharmaceutically acceptable acid addition salts thereof are described. The compounds of formula I are active as calcium channel blockers and accordingly, are useful as agents for lowering blood pressure, and as agents for treating ischemia.