Preparation of Polyfunctionally Substituted Pyridine-2(1&amp;lt;i&amp;gt;H&amp;lt;/i&amp;gt;)-Thione Derivatives as Precursors to Bicycles and Polycycles

Fathi A Abu-Shanab,Sherif M Sherif,Mohamed I Hassan,Sayed A S Mousa

doi:10.4236/ijoc.2014.45035

Preparation of Polyfunctionally Substituted Pyridine-2(1&lt;i&gt;H&lt;/i&gt;)-Thione Derivatives as Precursors to Bicycles and Polycycles

Fathi A Abu-Shanab, Sherif M Sherif + Show 2 more

Open Access

https://doi.org/10.4236/ijoc.2014.45035

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Abstract

Reaction of acetylacetone with 1 mole of dimethylformamide dimethyl acetal (DMFDMA) affords enamine 2a which reacts with cyanothioacetamide to give pyridinethione 3a. Pyridinethione 3a reacts with methyl iodide, halogenated compounds, aromatic aldehyde and malononitrile/elemental sulfur to yiled compounds 7-10 respectively. Reactions of thioether 7 in ethanolic K2CO3, 1 mole DMFDMA and 4-(dimethylamino)benzaldehyde give compounds 11, 13, 14 respectively. Enaminone 12 can be prepared by reaction of compound 11 with DMFDMA. We have demonstrated some reactions in order to show the potential usefulness of the prepared compounds for the preparation of new bipyridyl compounds 15, 16, 18, bicyclic compounds 17 and uncommon tricyclic compounds 20, 21, 22 and 23 respectively using DMFDMA.

Highlights

Formamide acetals are useful reagents in organic synthesis; [1] [2] their main application has been used for functional group transformations [3], but they may be regarded as one-carbon synthons in the construction of carbon skeletons
One type of reaction, which is potentially valuable for the future purpose, is the reaction of N,N'-dimethylformamide dimethyl acetal (DMFDMA) with 1,3-dicarbonyl compounds 1 to give enamines 2 [2] [4] (Figure 1)
In conjunction of this work, we report here the reaction of acetylacetone 1a with one mole of N,N'-dimetylformamide dimethyl acetal (DMFDMA) in dry dioxane gave the corresponding enamine 2a

Summary

Introduction

Formamide acetals are useful reagents in organic synthesis; [1] [2] their main application has been used for functional group transformations [3], but they may be regarded as one-carbon synthons in the construction of carbon skeletons. The compound 21a is treated with N,N'-dimetylformamide dimethyl acetal (DMFDMA) in dry xylene afforded the corresponding enamine 8-(3-(dimethylamino)acryloyl)-7-methyl-3-(p-tolyl)pyrido[3',2':4,5] thieno[3,2-d][1,2,3]triazin-4(3H)-one 23 in a good yield, Scheme 4.

Results

Conclusion