2.6- Dichloro-5-fluoronicotinoyl chloride

The N-acylation product of the reaction of enaminones with either 2-chloronicotinoyl chloride or 2,6-dichloro-5-fluoronicotinoyl chloride readily undergoes cyclization (either directly or on treatment with sodium hydride) to give high yields of 8-acyl-7-alkyl[l,6]naphthyridin-5(6//)-ones, which themselves are attractive precursors for elaboration to naphtho[2,3-, ][l,6]naphthyridin-5-ones and pyrido[2,3-f][l,6]naphthyridin-6-ones <2002T58>. 

A simple procedure is described for the preparation of substituted 1,6-naphthyri-dinones in good yields from the dianions of 2-methylnicotinic acids (2002A80), 2-chloronicotinoyl chloride or 2,6-dichloro-5-fluoronicotinoyl chloride (2002T8543) and a-oxoketene <3,A-acetals (2003MI2). 

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