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The reaction between 3-(dimethylamino)/3,3-bis(methylthio)-1-(substituted)prop-2-en-1-ones and 4-substituted-5-amino-1H-pyrazoles afforded new pyrazole[1,5-a]pyrimidines structurally related to Zaleplon. The chemical modifications introduced at the 3-, 5-, and 7-positions of the bicyclic structure revealed new promising candidates for the treatment of sleep disorders.