There is provided a compound of formula (I) wherein R1, R2a, R2b, R3a, R3b, R4, R5, R6, A, G and L have meanings given in the description, which compounds are useful as, or are useful as prodrugs of, competitive inhibitors of trypsin-like proteases, such as trombin, and thus, in particular, in the treatment of conditions where inhibition of thrombin is beneficial (e.g. conditions, such as thrombo-embolisms, where inhibition of trombin is required or desired, and/or conditions whereas anticoagulant therapy is indicated).