Disclosed are compounds of formula:
1
and pharmaceutically acceptable salts and esters thereof, useful in treating and/or preventing Alzheimer's disease and other similar diseases, wherein R
N
, R
C
, R
1
, n and R
20
are defined herein. These compounds include inhibitors of the beta-secretase enzyme that are useful in the treatment of Alzheimer's disease and other diseases characterized by deposition of A beta peptide in a mammal. The compounds of the invention are useful in pharmaceutical compositions and methods of treatment to reduce A beta peptide formation.