Two metal-free syntheses of 2,4,6-trisubstituted pyridines 10a-m and 16a-j are described. N, N, pyridin-2-amines 10 were prepared from aryl or heteroaryl methyl ketones which were transformed with N,Ndimethylacetamide dimethyl acetal (DMADMA) into enaminones 4a-m, followed by treatment with ammonium acetate to give (Z)-3-amino-1-(substituted)but-2-en-1-ones 5a-m. These were treated with DMADMA under microwave irradiation in a closed vessel at 1308C, to give via intermediates 7-9 the final products 10a-m. N 2 ,N 2 ,N 4 ,N 4 -Tetramethyl-6-(substituted) pyridine-2,4-diamines 16a-j were prepared in a one-pot synthesis from the corresponding carboxamides 11a-j by treatment with an excess of DMADMA in a closed vessel under microwave irradiation to give via intermediates 12a-j to 15a-j the final products 16a-j. X-Ray single crystal diffractometry studies of the enaminones 5c, 5g, 5i, 5j, and 5m and 2,4,6-trisubstituted pyridines 16a, 16b, 16g, 16i, and 16j were consistent with the expected structures.

Synthesis and Transformations of Alkyl 1,5-Bis(dimethylamino)-3oxopenta-1,4-diene-2,4-dicarboxylates. A Simple Synthesis of Dialkyl 1-Substituted 4-Oxo-1,4-dihydropyridine-3,5-dicarboxylates.-Acetonedicarboxylates [cf. (I)] react with DMF dimethyl acetal (II) to yield bisadducts (III) which are used as intermediates in a one-pot procedure for the synthesis of pyridones (V) (20 examples).

1,5-Diphenylpentane-1,3,5-trione (1) was transformed by the reaction either with N,N-dimethylformamide dimethyl acetal (DMFDMA) or N,N-dimethylacetamide dimethyl acetal (DMADMA) into (N,N-dimethylamino)methylidene derivatives 2a,b as intermediates. They were converted in the presence of silica gel into 5-benzoyl-2-phenylpyran-4-one (3a) and its 6-methyl derivative 3b, while the corresponding 5-benzoyl-2-phenylpyridin-4(1H)-one (4) was formed by the reaction with NH 4 Cl. Compound 3b gave the corresponding (N,N-dimethylamino)methylidene derivative 5 with DMFDMA, which was cyclized in aqueous ammonia into 2,5-diphenyl-4H-pyrano[3,2-c]pyridin-4-one (7). The reaction of 1 with excess of DMFDMA followed by reaction with ammonia or primary amines yielded 1-substituted 3,5-dibenzoylpyridin-4(1H)ones (9a-m).

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