The 5,6,7,8-tetrahydroimidazo[1,2-a]pyrazine derivative BIM-46174 has received attention as Gα_q inhibitor. We conducted structural reductions to monocyclic and bicyclic substructures to explore the chemical space of BIM fragments and to gain insights into the pharmacophore of BIM-type Gα_q inhibitors. Two piperazin-2-one-containing fragments and a small library of bicyclic lactams featuring fused pyrazine and diazepine rings were synthesized and evaluated. The results of a second messenger-based cellular assay indicate that the entire BIM structure is required for efficient Gα_q inhibition.