5,10-Dihydro-2-methyl-4H-thieno[2,3-b][1,5]benzodiazepin-4-one is a key intermediate in the synthesis of thienobenzodiazepine derivatives, particularly for atypical antipsychotic drugs such as olanzapine. These compounds modulate dopamine D2 and serotonin 5-HT2A receptors, making them valuable for treating schizophrenia, bipolar disorder, and other psychotic conditions. The fused heterocyclic structure provides enhanced receptor binding affinity, metabolic stability, and selectivity, aiding in the development of CNS agents with improved efficacy and reduced extrapyramidal side effects.