Introduction
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).
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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2,6-Bis[6-cyano-2-phenylpyrazolo[1,5-a]pyrimidin-7-yl]pyridine( 13)
Yield (0.423g, 82 %), mp:280 o C. IR (KBr) v cm-1: 2215 (CN),
1HNMR (DMSO-d6):
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.
2,6-Bis[5-cyano-pyrimido[1,2-a]benzimidazol-6-yl]pyridine(18)
Yield(0.405g,87 %), mp: 285 o C. IR (KBr) v cm-1: 2198, (CN).
1HNMR (DMSO-d6):
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.
2,6-Bis[6-cyano-[1,2,4]triazolo[1,5-a]pyrimidin-7-yl]pyridine(21)
Yield (0.295g, 81 %), mp: ----o C.
IR (KBr) v cm-1:
1HNMR (DMSO-d6):
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.
This week’s lab was the third and final step in a multi-step synthesis reaction. The starting material of this week was benzil and 1,3- diphenylacetone was added along with a strong base, KOH, to form the product tetraphenylcyclopentadienone. The product was confirmed to be tetraphenylcyclopentadienone based of the color of the product, the IR spectrum, and the mechanism of the reaction. The product of the reaction was a dark purple/black color, which corresponds to literature colors of tetraphenylcyclopentadienone. The tetraphenylcyclopentadienone product was a deep purple/black because of its absorption of all light wavelengths. The conjugated aromatic rings in the product create a delocalized pi electron system and the electrons are excited
...e 3. Both letters A and B within the structure of trans-9-(2-phenylethenyl) anthracene, that make up the alkene, have a chemical shift between 5-6 ppm and both produce doublets because it has 1 adjacent hydrogen and according to the N + 1 rule that states the number of hydrogens in the adjacent carbon plus 1 provides the splitting pattern and the number of peaks in the split signal, which in this case is a doublet.1 Letters C and D that consist of the aromatic rings, both are multiplets, and have a chemical shift between 7-8 ppm. 1H NMR could be used to differentiate between cis and trans isomers of the product due to J-coupling. When this occurs, trans coupling will be between 11 and 19 Hz and cis coupling will be between 5 and 14 Hz, showing that cis has a slightly lowered coupling constant than trans, and therefore have their respective positions in a product. 2
Step 2: Diethyl 2, 4-dichloro-5-fluorobenzoylmalonate is partially hydrolyzed and decarboxylated with tosylic acid to yield ethyl 2, 4-dichoro–5 fluorobenzoylacetate (17).
Despite the insolubility of the reagents in water, this medium was effective for the Wittig reactions involving various ylides without affecting the isomeric ratio. The improvement was more significant with aromatic and long-chain aldehydes that induced large hydrophobic effects. Consequently, water’s ability in stabilising the polar transition state and in reducing the energy of solvation through hydrophobic associations were suggested to cause the improved reaction rates and selective yields.10
The goal of this lab is to synthesize maleic anhydride with polyethylene glycol of 200g/mol molecular weight (PEG 200) and 2,3-dimethyl-1,3-butadiene to get 4,5-dimethylcyclohexane-1,2-dicarboxylic acid anhydride and its diacid by using Diels-Alders reaction and hydrolysis, respectively. The crystals were determined using melting point determination and IR spectroscopy.
By comparing the overall percent yields based upon pathway, the statistically superior pathway proved to be the Red pathway, which also happens to be the synthesis pathway I implemented. I determined that this was the best pathway based on the mean, median, and maximum overall percent yields of each pathway and are shown on Table 2. I hypothesize that this pathway was most successful because of the order of the reagents used, specifically that the nitration was the second step. I hypothesize that the addition of the nitro group to the benzoic acid was more successful than other reaction pathways because the attached carboxylic acid group is a moderate deactivator and meta director, more so than the attached ketone in the Blue pathway or the attached ester in the Green
found to have a melting point of 138 degrees (C). As before, of course this
This experiment sought to utilize melting point, boiling point, infrared (IR) spectroscopy, and the index of hydrogen deficiency (IHD) to identify the structures of two unknown compounds. To ensure the successful identification of the unknowns, the molecular formula for each compound was found first. What the molecular formula does is that it allows chemists to identify elements present in a compound as well as the quantity of each element. The issue with this is that there are various compounds that share the same molecular compound yet are different in reactivity and connectivity. To resolve this problem, other measures such as finding functional groups based on IR spectroscopy, determining the boiling or melting point of a compound, and identifying the bond/ring structures using IHD are taken.
Rogers, D. H.; Morris, J. C.; Roden, F. S.; Frey, B.; King, G. R.; Russkamp, F. W.; Bell, R. A.; Mander, L. N. Pure Appl. Chem., 1996, 68, 515.
Traditionally cyanide was used as a catalyst in this reaction since Von Liebig first discovered it in his research with almond oil. However, cyanide is very poisonous and harmful to health. More recently it was discovered that Vitamin B1, a coenzyme by the name of thiamine hydrochloride may be used to catalyze the benzoin condensation, which is preferable to using cyanide. This experiment will test whether thiamine can effectively catalyze the reaction (2).
...le of the specific binding to metal molecular cations. 18-crown-6 and 15- crown ethers are used for the recrystallization of AN from non aqueous solvents. The crystals formed by this method showed decrease in hygroscopicity . T. Lee et al. used crown ethers to minimize the polymorphic transition near room temperature. The room temperature phase transition is minimized by forming 1:1 co-crystal of AN-benzo-18-crown-6 with a melting point of 125-129 0C. One disadvantage of this Phase stabilized AN is that it reduces the burn rate of the propellant. Organic compounds, those are having crystallographic structure close to AN crystalline structure are also used as phase stabilizers. N. Galavina et al. have been studied the phase stabilization of AN using the organic compounds containing plane unsaturated N-Heterocycles substituted by carbonyl, amine or imine groups.
Recently, several chemical synthetic cross-linkers have also been developed having superior cross-linking properties [27]. In particular, 4-aminoethanol-N-hydroxyethanyl-1,8- naphthalimide (AHN), a dual-hydroxyl naphthalimide derivative that have been utilized in fluorescent labeling and as the chemical cross-linking agent but with less toxicity [28].
...Hallert, C., C. Grant, S. Grehn, C. Grannot, S. Hultent, G. Midhagens M. Strom, H. Svensson,
Schreuder, Jolanda A. H.; Roelen, Corné A. M.; van Zweeden, Nely F.; Jongsma, Dianne; van der Klink, Jac J. L.; Groothoff, Johan W.
Inorganic chemistry–II (Structure and mechanism in inorganic and organometallic chemistry, bonding, group theory, basic solid-state chemistry, and spectroscopic techniques.