A pharmaceutically useful compound which lowers blood cholesterol levels having the formula ##STR1## wherein X is oxygen or --NH--; Ar is phenyl, substituted phenyl, naphthyl or substituted naphthyl; R.sub.1 is hydrogen, lower alkyl or benzyl; and R.sub.2 is a straight or branched alkyl group having from 5 to 17 carbon atoms which may be substituted on the 1-carbon position with methyl, ethyl, phenyl, or substituted phenyl, or a cycloalkyl group having from 3 to 8 carbon atoms.