Amide compounds as boosters of antivirals

A compound of the formula

• the salts and stereoisomeric forms thereof, wherein
• R is H, phenyl, pyridyl, C1-6alkyl or
• wherein A and B are independently from each other H;
• C1-6alkyl optionally substituted with alkynyl, heteroaryl or a heteroatom selected from nitrogen, oxygen or sulfur which is optionally substituted with C1-6alkyl;
• or wherein A and B together with the nitrogen to which they are attached form a 5 or 6 membered saturated, partially or completely unsaturated heterocyclic ring containing 1 to 4 hetero atoms each independently selected from nitrogen, oxygen or sulfur, said heteroatoms are optionally substituted with C1-6alkyl;
• R1 is selected from the group comprising
• R2 is C1-6alkyl optionally substituted with OH, aminoalkyl, pyrrolidinyl, morpholinyl, alkynyl or C3-7cycloalkyl optionally substituted with halogen;
• R3 is OH;
• R4 is H or alkyl;
• R5 is pyridyl or phenyl optionally substituted with halogen;
• X is O, S or N optionally substituted with C1-6alkyl.