1H-​Pyrrolo[3,​4-​d]​pyridazin-​1-​one, 2,​6-​dihydro-​7-​[(3-​hydroxypropyl)​thio]​-​2-​methyl-​4-​(2-​methylpropyl)​-​6-​(1-​naphthalenylmethyl)​-