Enaminone derivatives are highly reactive intermediates extensively used for synthesis of otherwise not readily obtainable, heterocyclic compounds [1-4] and it can be used as starting material for the preparations of N-1 and /or N-2 substituted pyrazoles [29-31]. On the other hand a great deal of interest has been focused on the synthesis of the functionalized pyridine derivative owing to their biological activities [5-8].
In view of these observations and in continuation of our previous work directed towards development synthetic approach for the construction of biologically active heterocycles[9-12], we report herein a facile rout to various pyrazoles , isoxazoles, pyrimidines, pyrazolopyrimidine and triazolopyrimidine incorporated into pyridine moieties at position 2 and 6.
In this manner we have found that 2, 6-Bis [3-oxo-3-propanenitrile-2-(N, N-dimethyl amino) methylene] pyridine (3) is an excellent bulding blook for the synthesis of the entiled objectives
Results and discussion
Treatment of 2,6-Bis(3-oxo-3-propanenitrile) pyridine(2) with dimethyl formamide – dimethyl acetal (DMF-DMA) in dry THF at room temperature afforded a yellow crystalline product identified as 6-bis [3-oxo-3-propanenitrile-2-(N, N-dimethyl amino) methylene] pyridine (3)(scheme 1).
The reactivity of the enaminonitrile 3 towards some nitrogen nucleophiles was investigated. Thus, treatment of compound 3 with hydrazine hydrate in refluxing ethanol, afforded a colourless prouduct for which three possible structures 4a, 5a and 6a can be formulated. The spectral data of the isolated product was in complete agreement with structure 4a. Similarly, compound 3 reacted with phenyl hydrazine in refluxing ethanol in the presen...
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Yield (0.423g, 82 %), mp:280 o C. IR (KBr) v cm-1: 2215 (CN),
MS m/z (%): 515(M+), 346 315 (17), 77 (100). Analysis for C 31H 17 N 9 (515.54), Calcd: C, 72.22; H, 3.32; N, 24.45. Found: C, 72.25 H 3.37, N, 24.40.
Yield(0.405g,87 %), mp: 285 o C. IR (KBr) v cm-1: 2198, (CN).
MS m/z (%):346 (M+, 68), 315 (17), 77 (100).
Analysis for C 27H 13 N 9 (463.45) Calcd: C, 69.97; H, 2.83; N, 27.20. Found: C, 70.10 H, 2.85; N, 27.25.
Yield (0.295g, 81 %), mp: ----o C.
IR (KBr) v cm-1:
MS m/z (%):
Analysis for C 17H 7 N 11 (365.31), Calcd: C, 55.89; H, 1.93; N, 42.18. Found: C, 62.30; H, 4.10; N, 24.20.