Novel compounds of the formula ##STR1## or a pharmaceutically acceptable salt thereof, wherein: R.sub.1 is ##STR2## R.sub.2 and R.sub.3 are independently selected from --CH.sub.2 --, --CH(lower alkyl)--, --C(di-lower alkyl)--, --CH.dbd.CH-- and --C(lower alkyl).dbd.CH--; or R.sub.1 with R.sub.2, or R.sub.1 with R.sub.3, form --CH.dbd.CH-- or --CH.dbd.C(lower alkyl)--; u and v are independently 0-3, provided both are not zero; R.sub.4 is B--(CH.sub.2).sub.m C(O)--; m is 0-5; B--(CH.sub.2).sub.q --; q is 0-6; B--(CH.sub.2).sub.e --Z--(CH.sub.2).sub.r ; Z is --O--, --C(O)--, phenylene, --N(R.sub.8)-- or --S(O).sub.0-2 --, e and r is 0-5; the sum of e and r is 0-6; B--(C.sub.2 -C.sub.6 alkenylene)--; B'--(C.sub.4 -C.sub.6 alkadienylene)--;B--(CH.sub.2).sub.t --Z--(C.sub.2 -C.sub.6 alkenylene)--; t is 0-3; the sum of t and the number of carbon atoms in the alkenylene chain is 2-6; B--(CH.sub.2).sub.f --V--(CH.sub.2).sub.g --; V is cycloalkylene, f is 1-5, g is 0-5; the sum of f and g is 1-6; B--(CH.sub.2).sub.t --V--(C.sub.2 -C.sub.6 alkenylene)-- or B'--(C.sub.2 -C.sub.6 alkenylene)--V--(CH.sub.2).sub.t --; the sum of t and the number of carbon atoms in the alkenylene chain is 2-6, B--(CH.sub.2).sub.a --Z--(CH.sub.2).sub.b --V--(CH.sub.2).sub.d --; a, b and d are 0-6; the sum of a, b and d is 0-6; T--(CH.sub.2).sub.s --; T is cycloalkyl, s is 0-6; or R.sub.1 and R.sub.4 together form ##STR3## B is optionally-substituted phenyl, indanyl, indenyl, naphthyl, tetrahydronaphthyl or optionally substituted-heteroaryl; and R.sub.20 and R.sub.21 are independently optionally-substituted phenyl, optionally-substituted naphthyl, indanyl, indenyl, tetrahydronaphthyl, benzodioxolyl, optionally-substituted heteroaryl, optionally-substituted benzofused heteroaryl or cyclopropyl, pharmaceutical compositions, the use as hypocholesterolemic agents, processes for preparing, and the use in combination with cholesterol biosynthesis inhibitors to treat or prevent athersclerosis.