"lkyl, carboxyalkyl, alkoxycarbonylalkyl, aralkoxycarbonylalkyl, formyl, acyl, acylalkyl, alkylsulfonyl or aralkylsulfonyl; R and R' together may form a 5-7 atom ring which may include 0-2 hetero atoms of N, O or S; Rn is hydrogen or loweralkyl provided at least one of R, R', R and R' is other than hydrogen; and the non-toxic acid addition salts thereof. 2." . . . .