Beta-lactam cholesterol absorption inhibitors

A compound of Formula (Ia) or (Ib):

• wherein R represents
• a) hydrogen;
• b) —C(═O)—C1-6alkyl-C6H4R3, —C(═O)—C1-6alkenyl-C6H4R3 or —C(═O)—C6H4R3;
• c) —C1-6alkyl-C6H4R3 or —C1-6alkenyl-C6H4R3, wherein said —C1-6alkyl or —C1-6alkenyl is substituted by OH;
• R1 represents —OH or —OMe;
• R2 represents a halogen or —OMe;
• R3 represents hydrogen, a halogen, —OMe, —NO2 or —OH;
• or a salt thereof.