ChemInform Abstract: Tele Nucleophilic Aromatic Substitutions in 1-Nitro-3- and 1,3-Dinitro-5-trichloromethylbenzene, and 3-Trichloromethylbenzonitrile. A New Synthesis of the 1,4-Benzothiazine-3(4H)-one Ring System from 3-Nitrobenzoic Acid (original) (raw)
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Tetrahedron, 2000
3-Trichloromethylnitrobenzene 2, 1,3-dinitro-5-trichloromethylbenzene 13 and 3-trichloromethylbenzonitrile 18 react with sodium methoxide to give 4-methoxy-3-nitrobenzaldehyde 6, 4-methoxy-3,5-dinitrobenzaldehyde 15 and 5-dimethoxymethyl-2-methoxybenzonitrile 19, respectively. Compounds 2 and 13 react with methyl thioglycolate to afford dichloromethylacetates 7 and 16, respectively. These products are the result of tele nucleophilic aromatic substitution. Compound 18 reacted with methyl thioglycolate to give acetate 20 resulting from nucleophilic displacement
International Journal of Chemistry, 2013
The hydrazinolysis of 2,4-dinitrophenyl acetate in methanol proceed exclusively through acyl-oxygen scission by a concerted mechanism. The reaction of 1-chloro-2,4-dinitrobenzene with hydrazine in methanol, acetonitrile and dimethyl sulfoxide undergo uncatalyzed substitution and the formation of the zwitterionic intermediate is the rate-determining step. While 2,4-dinitrobenzene derivatives 1, 2, 3, 4, 5a-i, 6 with hydrazine in DMSO undergo uncatalyzed substitution and the departure of the leaving group is the rate-determining step. The process depends on the basicity of the leaving group and its steric hindrance as well as the possible intramolecular hydrogen bond in the transition state. The reactivity of compounds 5a-i depends on the substituent of the thioaryl ring while the small ρ Y value is due to the sulfides existing preferentially in the skew conformation. The small β lg value (-0.18, r = 0.99) indicated that the reaction of sulfides with hydrazine proceeds with advanced bond formation to the nucleophile and the bond cleavage proceed in a slow extent in the transition state.
The vicarious nucleophilic substitution in some nitroindazole and nitrobenzotriazole derivatives with tertiary carbanions leads almost exclusively to products substituted para to the nitro group. As results from the theoretical calculations and structural evidences, such reaction outcome is due mainly to the stereoelectronic reasons in combination with the considerable shortening of the C ortho -CNO 2 bond. The presence of the chiral and prochiral centres (the methine and Nmethylene groups, respectively) often gives rise to additional splitting of the methylene protons signal that is transmitted on a long distance provided there is no pyridinic nitrogen in the pathway of coupling.
3-Halomethylated cyclic nitronates: synthesis and nucleophilic substitution
Tetrahedron, 2011
A method for the introduction of a halogen atom into the methyl group attached to the C-3 atom of fiveand six-membered cyclic nitronates (isoxazoline N-oxides and oxazine N-oxides, respectively) has been studied. The process involves silylation of starting 3-methyl-substituted cyclic nitronates followed by halogenation of the resulting N-(silyloxy)enamines. While fiveand six-membered cyclic enamines behave similarly toward elemental bromine and iodine, their reactions with NBS give different products, that were rationalized by stereoelectronic effects. The obtained halogenated nitronates were coupled with various nucleophiles affording new nitronates functionalized at the C-3 position.
Synthesis of Nitroaromatic Compounds via Three-Component Ring Transformations
Molecules, 2021
1-Methyl-3,5-dinitro-2-pyridone serves as an excellent substrate for nucleophilic-type ring transformation because of the electron deficiency and presence of a good leaving group. In this review, we focus on the three-component ring transformation (TCRT) of dinitropyridone involving a ketone and a nitrogen source. When dinitropyridone is allowed to react with a ketone in the presence of ammonia, TCRT proceeds to afford nitropyridines that are not easily produced by alternative procedures. Ammonium acetate can be used as a nitrogen source instead of ammonia to undergo the TCRT, leading to nitroanilines in addition to nitropyridines. In these reactions, dinitropyridone serves as a safe synthetic equivalent of unstable nitromalonaldehyde.
Zeitschrift für Naturforschung B, 1986
3-Thiocyanatomethyl C innam onitrile, R eductive Cleavage, Pyrrole Derivatives /3-Thiocyanatomethyl cinnam onitrile derivatives coupled with aromatic diazonium salts to afford the corresponding azo com pounds, which undergo reductive cyclization into pyrrole derivatives. The utility of organic cyano com pounds in heterocyclic synthesis has recently received consider able attention [1, 2], Our group has been involved in the last years in a program aiming to develop effi cient procedures for synthesis of polyfunctionally substituted azoles [3, 4], azines [5, 6 ] and their con densed derivatives [7, 8 ] utilizing simple and readily obtainable polyfunctionally substituted nitriles. D u ring this phase of our research we could show that whereas ethylidenem alononitrile derivative l a does not couple with aromatic diazonium salts, the pre sence o f cyano substituent on the methyl m oiety (as in lb ) sufficiently activates the adjacent m ethylene group for coupling [9], The resulting hydrazones could be utilized for synthesis of pyridazine-6 -imine derivatives [10]. It seem ed to us of value to see if the presence of other functional substituent on the methyl m oiety in 1 can effect similar activation.
New Routes for the Synthesis Novel Heterocyclic via Formation of C-N Bond and via Cleavage a Thiazine Ring of 1,4-Benzothiazine, 2016
The reactions of 2-aminothiophenol with acetylacetone in refluxing DMSO or ethanol was investigated. Treatment of 1 with enaminone 5 gave benzothiazine derivative 6. A reasonable mechanism to account for the formation of pyridone derivative 11 by treatment of 2 with malononitrile. Reactions of 2 with cyanoacetic hydrazide, thiosemicarbazide, and hydrazine hydrate and phenyl hydrazine afforded the compounds 13, 15 and, 17a-b respectively. Condensation of 13 with 4-methoxy benzaldehyde gave 18. The latter compound reacted with malononitrile gave pyridone derivative 19. A reasonable mechanism account for the formation of pyrazolo[3,4-b]pyridine derivative 20 from the reaction of 13 with DMF-DMA via cleavage of a thiazine ring of benzothiazine. The structures of all newly synthesized compounds elucidated by elemental analysis 1 H-NMR and 13 C-NMR spectra, Ms and X-ray crystallographic investigations. The reported crystal structures of these novel benzothiazine derivatives are expected to be a remarkable contribution to the crystallographic database of heterocyclic compounds.
Journal of Heterocyclic Chemistry, 2018
Ten new isoxazoline derivatives were synthesized from the reactions of benzonorbornadiene and homonorbornadiene derivatives with nitrile oxides formed from benzaldehyde and 4-substituted benzaldehyde. Two new pyridazine derivatives were also synthesized from the reaction of the homonorbornadiene derivatives with 3,6-di (2-pyridyl)-s-tetrazine. It was seen that all cycloaddition reactions were realized as exo selectivity. Finally, γ-Gauche effect in the isoxazoline derivatives was discussed.