Diels-Alder in Heterocyclic Synthesis: A Novel Synthesis of Cycloalkanopyridazinimine, 1,7-alkanothienopyridazines and 1,8-alkanophthalazines: New ring system

Al‐Omran, Fatima; Al-Awadhi, Nouria; El‐Khair, Adel A.

doi:10.3184/030823400103165743

Cited by 18 publications

(14 citation statements)

References 9 publications

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“…This find parallel to reported C-1 alkylation of thienocoumarins and thienonaphthobenzopyran on reaction with enaminones [7]. Further confirmation of structure was obtained via HMQC -2D spectroscopy that enabled assignment of 13 C NMR spectra.…”

Section: Introductionsupporting

confidence: 64%

“…Aminofunction, C-1 as well as the diene system are all possible sites of attack. However, in no case thiepins has resulted from such additions as has been claimed earlier [13].…”

Section: May-jun 2006mentioning

confidence: 98%

“…Found C,61.71;H,5.22;N,8.79;S,amino]-7-methyl-4-oxo-3-p-tolyl-3,4-dihydrothieno [3,4-d] 7,197.6,164.5,158.0 (CO),148.7,146.4,138.5,135.9,130.2,129.6,126.3,125.5,124.2,116.5,112.3,53.8 ,4.69;N,9.31;S,7.10. Found C,61.23;H,4.97;N,9.47;S,-amino]-7-methyl-4-oxo-3-p-tolyl-3,4-dihydrothieno [3,4-d] 13 C nmr (deuteriochloroform): 200. 5,197.2,164.5,159.1 (CO),148.0,146.5,138.6,137.9,135.9,130.5,129.9,126.2,124.1,116.4,111.2,53.8 (OCH 3 ), 52.2 (cyclohexane carbon),.…”

Section: General Procedures For the Preparation Of Compounds 21-23mentioning

confidence: 99%

“…The cis-trans diene structures 18a,b and 19 were assigned based on 1 H NMR that revealed cis olefinic proton doublet of doublet as well as a trans olefinic doublet. Assignment of 13 C NMR was made after inspection of HMQC -2D spectra of the reaction product.…”

Section: Introductionmentioning

confidence: 99%

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Studies with condensed aminothiophenes: Further investigation on the reactivity of condensed aminothiophenes toward electron poor and acetylenes under microwave heating

Al-Saleh

El‐Apasery

2006

Journal of Heterocyclic Chem

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The reaction of aminothienopyridazines 8a,b, aminothienocoumarin 13 and aminothienonaphthopyran 14 with enaminones 9, 17 and 20a,b under microwave irradiation affords either a mixture of both condensations C‐1 alkylation products 15 and 16 or amino moiety alkylation and diethylamine elimination or only one of these products depending on nature of substituents on the thiophene ring. On the other hand reaction of these condensed aminothiophenes with 3‐dimethylaminoacrylaldehyde afforded 24 and 25.

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Section: Introductionsupporting

confidence: 64%

“…Aminofunction, C-1 as well as the diene system are all possible sites of attack. However, in no case thiepins has resulted from such additions as has been claimed earlier [13].…”

Section: May-jun 2006mentioning

confidence: 98%

Section: General Procedures For the Preparation Of Compounds 21-23mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Studies with condensed aminothiophenes: Further investigation on the reactivity of condensed aminothiophenes toward electron poor and acetylenes under microwave heating

Al-Saleh

El‐Apasery

2006

Journal of Heterocyclic Chem

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“…It is assumed that hippuric acid, first cyclizes into the oxazolone 19, which then reacts with the enaminone 3a, yielding 20, that further rearranges into the pyranone 21. A similar reaction sequence has recently been proposed by us to account for the formation of pyranones from the reaction of enaminones with hippuric acid 9 .…”

mentioning

confidence: 82%

Studies with 2H pyranones: Synthesis of new 3-substituted-4-hydroxy-2H-pyran-2-ones

Al-Saleh

Al‐Awadi

Al-Kandari

et al. 2000

Journal of Chemical Research

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In conjunction with our interest in exploring the synthetic potential of enaminones, 7 we report here on the synthesis of 3a,b and their utilities for the synthesis of 3-heteraromatic 2Hpyran-2-one derivatives. Thus compound 3a was prepared in 70% yield by reacting 1a with N,N-dimethylformamide dimethyl acetal in refluxing dioxane. This procedure proved better than the literature procedure, 8 which produced some side products along with 3a. The Z-form 4a was not detected. The 1 H NMR spectra of the reaction product revealed only two mutually coupled trans olefinic protons at δ = 6.53 and δ = 8.17 ppm (J = 14Hz). IR spectrum of the reaction product revealed strong CO absorption at 1712 cm -1 for 2H-pyran-2one carbonyl group while OH appeared as weak broad band at 3,500 -3,300 cm -1 which indicates that 3a exists in the hydrogen bonded form 5.The 13 C NMR spectra of the reaction product revealed enaminone carbonyl carbon at δ 186 ppm, which is in accordance with the proposed structure. The observed magnetic non-equivalence of the two methyl functions of the dimethyl amino moiety is believed to result from restricted rotation around CH = N bond in charge separated form 6.Treatment of 3a with malonoitrile in refluxing ethanolic piperidine afforded a product of condensation with water elimination. The 13 C NMR spectra indicated the presence of only one CN signal. The isometric structures 7 and 11 seemed reasonable. Structure 11 was tentatively proposed, on the basis of the stability of the product, in acetic acid under reflux in the presence of aqueous hydrochloric acid. These conditions are expected to convert 7 to 8. It is thus believed that 11 is formed by initial condensation of the ring carbonyl with the active methylene moiety in malononitrile yielding 9 which cyclizes into 11 via the intermediate 10 (Scheme 1). The 1 H NMR spectra of compound 11 showed the characteristic pattern corresponding to an AB system at δ 7.95 and 8.03 ppm and J 13 Hz for vinylic trans protons.Reacting 3a with 1,4-benzoquinone 12 resulted in the formation of 14. Similarly, reacting 3a with 1,4-naphthoquinone 15 afforded 17. The formation of 14 and 17 from 12 and 15, is assumed to occur via initial addition of the enaminone of, electron rich C-2, to the active double bond in 12 and 15 yielding the adducts 13 and 16, that cyclize into the final products.Compound 3a, also reacted with hippuric acid 18 in refluxing acetic anhydride to yield the pyranone 21. It is assumed that hippuric acid, first cyclizes into the oxazolone 19, which then reacts with the enaminone 3a, yielding 20, that further rearranges into the pyranone 21. A similar reaction sequence has recently been proposed by us to account for the formation of pyranones from the reaction of enaminones with hippuric acid 9 .Compound 3a reacted with methylamine, ethylamine and aniline in acetic acid at room temperature to yield enaminones, which were found to exist, as mixture of the E and Zforms 23a,c and 24a-c. The existence of Z-form for these compounds is in contrast to the observe...

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ChemInform Abstract: Diels—Alder in Heterocyclic Synthesis: A Novel Synthesis of Cycloalkanopyridazinimine, 1,7‐Alkanothienopyridazines and 1,8‐Alkanophthalazines: New Ring System.

2000

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Diels-Alder in Heterocyclic Synthesis: A Novel Synthesis of Cycloalkanopyridazinimine, 1,7-alkanothienopyridazines and 1,8-alkanophthalazines: New ring system

Cited by 18 publications

References 9 publications

Studies with condensed aminothiophenes: Further investigation on the reactivity of condensed aminothiophenes toward electron poor and acetylenes under microwave heating

Studies with condensed aminothiophenes: Further investigation on the reactivity of condensed aminothiophenes toward electron poor and acetylenes under microwave heating

Studies with 2H pyranones: Synthesis of new 3-substituted-4-hydroxy-2H-pyran-2-ones

ChemInform Abstract: Diels—Alder in Heterocyclic Synthesis: A Novel Synthesis of Cycloalkanopyridazinimine, 1,7‐Alkanothienopyridazines and 1,8‐Alkanophthalazines: New Ring System.

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