Heterocyclen durch Michael‐Reaktionen, 8. Mitt. Reaktionen von Hydroxymethylentetralon mit Cyanessigsäurederivaten

Otto, Hans‐Hartwig; Schmelz, Herbert

doi:10.1002/ardp.19823150609

Cited by 9 publications

(3 citation statements)

References 18 publications

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“…The average life of the intermediate 2 H -pyran-2-imine 6 must be very low. In the literature, we found described only those whose 2 H -pyran-2-imine rings are stable to nucleophilic attack because they are integrated in condensated polycyclic systems. ,− …”

Section: Resultsmentioning

confidence: 99%

“…The reactions of β-dicarbonyl compounds or β-functionalized α,β-unsaturated ketones with malononitrile and related compounds have been described as a synthetic method of 2(1 H )-pyridinones. − While the reaction mechanism with cyanacetamide seems to be firmly established, − the process by which malononitrile acts as a nucleophilic agent has been interpreted in according to different hypothetical mechanisms. ,,,− …”

Section: Introductionmentioning

confidence: 99%

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Regioselective Synthesis of 2(1H)-Pyridinones from β-Aminoenones and Malononitrile. Reaction Mechanism

Alberola¹,

Calvo²,

Ortega³

et al. 1999

J. Org. Chem.

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The identification of some intermediates of the reactions between β-aminoenones and malononitrile to give 2(1H)-pyridinones has allowed us to obtain valuable information concerning its mechanism. These reactions begin with a conjugated addition of the nitrile to the enone followed by elimination. The compounds thus obtained cyclize to nonisolable 2H-pyran-2-imine. This afforded 2(1H)pyridinones by ring opening to unsaturated aminoamides followed by cyclization (Dimroth-type rearrangement).

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Regioselective Synthesis of 2(1H)-Pyridinones from β-Aminoenones and Malononitrile. Reaction Mechanism

Alberola¹,

Calvo²,

Ortega³

et al. 1999

J. Org. Chem.

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“…For the enolates 6, the cyclization process could not be ascertained through the identification of other intermediates and probably results via amide formation or by a sort of Dimroth 22 rearrangement of a preliminary a-iminopyran ring. 23 The amide and salt nature of compounds 5 and 6 respectively has been clarified by IR, 1 H NMR and 13 C NMR spectral data. The formation of the isolated amides 5 was in agreement with the example reported by Krasnaya.…”

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confidence: 99%

An Efficient Synthesis of Functionalized 2-Pyridones by Direct Route or via Amide/Enolate Ammonium Salt Intermediates

Bondavalli¹

1999

Synthesis

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A number of compounds with a 2-pyridone structure 3, which have different substituents and are analogous to cardiotonic drugs like milrinone, have been synthesized in high yields from the appropriate enamino ketones 2 using different cyanomethylene active compounds (methyl cyanoacetate, benzoylacetonitrile and phenylsulfonylacetonitrile). In this synthetic route, the active role of the dimethylamine released in situ on the cyclization process has been underlined. In particular, its direct intervention, as a nucleophile or a base, was proven and intermediate amides 5 or enolate ammonium salts 6 were isolated and recognized by the analytical and spectral data.

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1,4‐pentandien‐3‐ones, XXXII: Reaction of 2‐acetylthiophene and 2‐acetylfuran with malononitrile and aldehydes, and synthesis and properties of phenylene‐bis [(thienyl/furyl)nicotinonitrile] derivative

Greiner-Bechert

Otto

1991

Archiv der Pharmazie

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The (E}-I-hetaryl-2-propen-I-ones 3 and 4 are prepared by condensation of 2-acetylthiophenes (1a,1c:.ld)or 2-acetylfuran (Ib) with aldehydes. The Michael addUC\S 5/6 areobtained from 3/4 by reactionwith malononitrile/1..DA in TIIF at -78OC. or in OMSOwith NaH at room temp.Reactionof 3/4 with malononitrile and methylate in methanol yielded the substituted nicotinonitriles 7/8. From terephthalaldehyde. the diketones 9 are prepared,whichyield with malononitrile the phenylene-bis[(thienyVfuryl)nicotinonitrilel derivatives 10 undersimiliarconditions. StruetUrat and spectraldata are discussed.2-Acetylated thiophenes and furans 1 are versatile starting materials for many classes of heterocyclesi', We are especially interested in the construction of highly substituted pyridines and related heterocycles starting from 1,4-pentadien-3-ones and other substituted C1,~unsaturated ketones by Michael and similiar reactions 3 ). Here, we report about the reactions of 1 with aromaticaldehydes2 and malononitrile.Referring to a prescription given by Murphy and Watta· nasin 4 ) la was reacted with the aldehydes 2a-i in absol. methanol in the presence of NaOH. The (l,l3-unsaturated ketones 3a-i (Scheme 1) were obtained in yields between 80 and 90%5). 3y was prepared from Ic, and 3z from Id, By a similiar procedure, from Ib the unsaturated ketones 4a-i were obtained.According to spectroscopic data, all compounds 3/4 exist in the E-configuration. Their IR-spectra show a strong carbonyl absorption around 1640 em", and the C=C absorption appears between 1590 and 1600 em", The out-of-plane vibration bond at 980 cm' is a characteristic of trans alkenes. form", a.13-Unsaturated ketones with E-configuration usually prefer the s-trans conformatlonv", As the propenones 3 and 4 contain the l,4-pentadien-3-one system -one double bond of the system is included in the heteroaromatic ring -it might be of interest to know, whether these compounds exist in different conformers as shown in Scheme 2. The system is flexible, and, therefore. an equilibrium of at least four conformations should be possible in solution, and it was of special interest to see if 3 and 4 even prefer one conformation. Perhaps, the i.r, spectra suggest a preferred sods conformation as indicated by the ratio Ico/Ic-e, and by the difference of 50-60 em" between both bands. Using the ASIS effect lO ) (deuterochloroforrn/deuterobenzene), we demonstrated that the s-transls-cis conformation A is the preferred one in solution. The differences in the shifts of the l3-protons, Sc6D6 -SCDC13' vary between +0.05 and +0.3 ppm ll ) (Table 1).

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Heterocyclen durch Michael‐Reaktionen, 8. Mitt. Reaktionen von Hydroxymethylentetralon mit Cyanessigsäurederivaten

Cited by 9 publications

References 18 publications

Regioselective Synthesis of 2(1H)-Pyridinones from β-Aminoenones and Malononitrile. Reaction Mechanism

Regioselective Synthesis of 2(1H)-Pyridinones from β-Aminoenones and Malononitrile. Reaction Mechanism

An Efficient Synthesis of Functionalized 2-Pyridones by Direct Route or via Amide/Enolate Ammonium Salt Intermediates

1,4‐pentandien‐3‐ones, XXXII: Reaction of 2‐acetylthiophene and 2‐acetylfuran with malononitrile and aldehydes, and synthesis and properties of phenylene‐bis [(thienyl/furyl)nicotinonitrile] derivative

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