A compound of formula I or a pharmaceutically acceptable salt, ester or prodrug thereof wherein the variables have the meanings as defined in the specification. Further disclosed are a method of inhibiting IKK activity using a compound of formula I, a method of inhibiting production of TNF using a compound of formula I, a compound of formula I for use as a pharmaceutical, a pharmaceutical composition comprising a compound of formula I, and use of a compound of formula I in the manufacture of a medicament for use as an immunosuppressant or anti-inflammatory agent. ##STR00001##