Zur Reaktion von Malonsäurederivaten mit Homophthalimiden Umlagerungen von Heterocyclen, 2. Mitt.

Zusammenfassung Die Homophthalimide 1 a–b reagieren mit monosubstit. Malonylchloriden in Gegenwart von N,N-Dimethylanilin zu den 4-Hydroxy-2-pyron-derivaten 4 a–d. Durch Erhitzen auf 200° werden diese Verbindungen in Dihydroxy-naphthalsäureimide (6) umgelagert. Die Aktivierungsparameter für die Reaktion 4 a6 a und 4 b6 b sind bestimmt worden. Die Verbindungen 6 a–f können auch direkt durch Umsetzung der Homophthalimide 1 a–b mit substit. Malonsäure-bis-2,4,6-trichlorphenylestern bei 240–260° gewonnen werden.

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Rearrangement reactions of heterocyclic compounds, II: The reaction of malonic acid derivatives with homophthalimides

The reaction of homophthalimides (1 a–b) and monosubstituted malonyl chlorides in the presence of N.N-dimethylaniline gives the 4-hydroxy-2-pyrone derivatives 4 a–d. These compounds are rearranged to dihydroxy-naphthalimides (6 a–d) when heated at about 200°. The kinetics of this reaction have been studied. Compounds 6 a–f are also obtained in high yield by the one step reaction between 1 a–b and 2.4.6-trichlorophenyl malonates 2 a–c at 240–260°.

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Herrn Prof. Dr.Erich Ziegler in Freundschaft und Verehrung zum 60. Geburtstag gewidmet.     

Synthese von Benzofuranen durch Cyclodehydrierung von Phenylmalonylheterocyclen

Phenylmalonyl heterocyclic compounds such as the quinolones1a–c or3, benzoquinolizinones6a, b and the phenalenones8a, b can be converted to benzofuranes (2a–c, 7a, b and9a, b) by cyclodehydrogenation with Pd/C in boiling diphenyl ether. 2-Phenylchinchonic acid (10) reacts under the same conditions to the dimeric benzofuroquinoline12: the decarboxylated quinoline11 however gives the monomer13.

Herrn Prof. Dr.G. Zigeuner zur Vollendung seines 60. Lebensjahres gewidmet.     

Conformation and reactivity of α-oxo-ketenes: Ab initio and semiempirical (AM1, PM3) calculations

Ab initio MP2/6-31G*//MP2/6-31G* and semiempirical AM1 and PM3 calculations on a series of differently substituted α-oxo-ketenes are used to investigate E/Z-isomerism and rotational barriers in these molecules. Sterically crowded derivatives are found to exist solely as s-E conformers. The unusual stability of these derivatives thus can be attributed to their inability to adopt the s-Z conformation required for the normal α-oxo-ketene reactions. With respect to structures and energies, the PM3 method (especially in the case of highly crowded molecules) is found to be less reliable than AM1. Ab initio HF/3-21G and PM3 vibrational frequencies appear to be of sufficient accuracy for a distinction between s-Z and s-E conformers. In this respect, the AM1 method appears less reliable. © 1994 by John Wiley & Sons, Inc.     

Synthesis of highly symmetric mesomeric triazaphenalene betaines

The synthesis of seven mesomeric triazaphenalene betaines 4a‐g by condensation reaction of hexahydro‐2H‐pyrimido[1,2‐a]pyrimidine 1 with diethyl malonates 2a‐g or with bis(2,4,6‐trichlorophenyl)malonates 3c,f has been achieved. The guanidine 1 forms in benzene solution a salt with trimethyl methanetricarboxylate 5 which upon heating produces 4a.     

Synthesis of functionalized 1,3-thiazine libraries combining solid-phase synthesis and post-cleavage modification methods

The solid-phase synthesis of diverse sets of 1,3-thiazine-5-carboxylates on Wang resin is described. Acetoacetylation, followed by Knoevenagel condensation and an acid-promoted ring-closure reaction with thioureas furnished polymer-bound 1,3-thiazines. As an alternative to transesterification, a de-novo synthesis of beta-keto esters, starting from polymer-bound malonic acid through reaction with acyl imidazoles, was applied to increase the diversity. To reduce contamination, an on-bead purification of resin-bound 1,3-thiazines that makes use of differences in the reactivity of ester bonds toward alkoxides is reported. A final four-step post-cleavage modification of thiazine-5-carboxylates, derived by TFA cleavage from the Wang linker, leads to esters or amides. Twenty 1,3-thiazines were obtained in yields of up to 61 % over either 9 or 13 steps.     

Synthesen von Heterocyclen, 136. Mitt.: Über Reaktionen mit Salicylsäurechlorid

Zusammenfassung N,N-Äthylen- bzw. N,N-Trimethylen-S-äthyl-isothioharnstoff (2 bzw.3) reagieren mit der doppeltmolaren Menge Salicyl-säurechlorid (1) zu den pentacyclischen Verbindungen4 und5.

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Syntheses of heterocycles, CXXXVI: Reactions with salicoyl-chloride

N,N-Ethylene- or N,N-trimethylene-S-ethyl-isothiourea (2 or3) react with 2 molecules of salicoyl chloride (1) yielding the pentacyclic compounds4 and5, resp.

     

Mesoionische Sechsringheterocyclen,XVI Syntheses von 2 a, 5 a-Diaza-acenaphthylen Mesoionen

Reaction of 7-azaindole with activated malonates (1) results in the formation of the tricyclic mesoionic diaza-acenaphthylene compounds2. Hydrogenation of2a with platin as catalyst leads to the saturated betaine4. The structure assignment was established by¹H-¹³C-NMR shift correlation and decoupling experiments.     

Ylide von Heterocyclen,III Pyridinium-Ylide von Malonylheterocyclen

Reaction of isatoic anhydride with the betaine esters2 or3 represents a new synthesis of pyridinium ylides of type5, which have been previously obtained by several other ways. Treatment of the ylide5 with inorganic acids results in the formation of their pyridinium salts5 a–d. Hydrogenation or dehydrogenation of5 with Pd/C give the piperidylquinoline9 or the betaine10, respectively. Both of them can be prepared by an alternative way. ThepK values of some pyridinium ylides were determined.

II. Mitteilung:Kappe Th., Korbuly G., Stadlbauer W., Chem. Ber.111, 3857 (1978).     

Synthesen von Heterocyclen, 69. Mitt.: Über eine Synthese des Indigotins

Zusammenfassung Im 3,3-Dichlor-2,4-dioxe-1,2,3,4-tetrahydrochinolin (I), welchesleicht zugänglich ist, lassen sich die Chloratome durch Alkoxybzw. Phenoxygruppen ersetven. Die hierbei entstehenden Chinisatin-ketale (II bis IV) werden durch wäßrige Alkalien unter Hydrolyse und Abgabe von CO₂ zu o-Aminophenylglyoxalacetalen (VI und VII) gespalten, welche beim Behandeln mit verd. Säuren in quantitat. Umsetzung Indigo geben. Die Reduktion der Chinisatin-ketale führt zu in 3 Stellung verätherten Carbostyrildiolen (VIII bis X).

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3,3-Dichloro-2.4-dioxo-1,2,3,4-tetrahydroquinoline (I) is converted readily to ketals of quinisatin (II–IV), which in turn give the corresponding acetals of o-aminophenylglyoxal (VI–VII) on refluxing in NaOH. Treatment with dilute acid converts the acetals VI or VII rapidly and quantitatively into indigo. Starting from I, indigo can be prepared in 90% yield in a single run and in the same reaction vessel by treating I in series with sodium methoxide, boiling 2N-NaOH and finally with dilute mineral acid.—The ketals of quinisatin (II–IV) are reduced quantitatively with zinc dust and acetic acid in ethanol to the carbostyrildiol-3-ethers VIII–X.

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Herrn KollegenR. Tschesche, Dir. des Organisch-chemischen Institutes der Universität Bonn, mit freundschaftlichen Grüßen und herzlichen Wünschen zum 60. Geburtstage.     

Halogenation reactions in position 3 of quinoline-2,4-dione systems by electrophilic substitution and halogen exchange

Summary 3-Substituted 4-hydroxy-2(1H)-quinolones3,5,7 are halogenated with bromine or sulfuryl chloride to yield the quinolinediones9 or10. Reaction of3,5,7 with chloroform gives the dichloromethyl quinolinediones11. Halogen exchange leads from the chloro quinolinediones10 to fluoro quinolinedones12 and to azido quinolinediones13. Similarly the dichloro quinolinedione10 an reacts to the difluoro quinolinedione14, which is reduced to the 3-fluoro-4-hydroxyquinolone16 and reacts again with sulfuryl chloride to give the mixed 3-chloro-3-fluoroquinolinedione15.Herrn Prof. Dr. Erich Ziegler in freundschaftlicher Verbundenheit zum 80. Geburtstag gewidmet.