1983 Volume 103 Issue 6 Pages 623-630
5, 8-Dichloropyrido[2, 3-d]pyridazine (I), in benzene in the presence of sodium amide, reacted with active methylene compounds ; ethyl cyanoacetate (IIa), ethyl acetoacetate (IIb), diethyl malonate (IIc), malononitrile (IId), phenylacetonitrile (IIe), to afford 5-substituted (R1)-8-chloropyrido[2, 3-d]pyridazine (III) or 8-substituted (R2)-5-chloropyrido[2, 3-d]pyridazine (IV) ; IIIa (R1=NC-C^^^〓H-CO2C2H5), IVa (R2=NC-C^^^〓H-CO2C2H5), IVb' (R2=-CH2CO2C2H5), IVc (R2=-CH(CO2C2H5)2), IIId (R1=-CH(CN)2), IVe (R2=NC-C^^^〓H-Ph). Compound I, in toluene in the presence of sodium hydride, also reacted with acetophenone (IIf), propiophenone (IIg) to afford 2-(5-chloro-8-pyrido[2, 3-d]pyridazinyl) acetophenone (VII), 2, 2'-(5, 8-pyrido[2, 3-d]pyridazinediyl) di-(1-phenylethanone) (VIII) ; 2-(5-chloro-8-pyrido[2, 3-d]pyridazinyl) propiophenone (XV) respectively. However, reaction of I with acetone (IIh), diethyl ketone (IIi) gave no 5 or 8-substituted pyrido[2, 3-d]-pyridazine der., but a mixture of structure-unknown products.
