CETP activity inhibitors

A CETP activity inhibitor comprising as an active ingredient a compound represented by formula (I):

• wherein
• R represents
• a straight chain or branched C2-10 alkenyl group;
• a halo-C1-4 lower alkyl group;
• a substituted or unsubstituted C5-8 cycloalkenyl group;
• a substituted or unsubstituted C3-10 cycloalkyl C1-10 alkyl group;
• or
• a substituted or unsubstituted 5- or 6-membered heterocyclic group having 1-3 nitrogen, oxygen, or sulfur atoms,
• X1, X2, X3, and X4 may be the same or different and represents
• a hydrogen atom;
• a halogen atom;
• a C1-4 lower alkyl group;
• a halo-C1-4 lower alkyl group;
• a C1-4 lower alkoxy group;
• a cyano group;
• a nitro group;
• an acyl group;
• or
• an aryl group,
• Y represents —SO2—, and
• Z represents a group of the formula
• wherein R, X1, X2, X3, X4, and Y are the same as described above;
• or a pharmaceutically acceptable salt thereof.