9-Chloro-dibenzo[b,f][1,4]thiazepin-11(10H)-one is an intermediate in the synthesis of 9-Chloro Quetiapine (C366040). 9-Chloro Quetiapine is an impurity of Quetiapine hemifumarate (Q510000), a dibenzothiazepine antipsychotic medication used in the treatment of schizophrenia.