1,2,3-Triazolidine durch Cycloaddition von Aziminen an Olefine

1,2,3-Triazolidines by Cycloaddition of Azimines to Olefines Azimines A can undergo [3+2]-cycloadditions with olefines B to give 1,2,3-triazolidines C , a class of hitherto unknown heterocycles. The three examples of this reaction realized here involved the azimine 1 with electron-withdrawing substituents and the olefines 2, 3 and 4 with an electron-donating substituent, yielding the cycloadducts 5,6 and 7 . The triazolidine structure of 5 was established by an X-ray diffraction analysis. Characteristic for 5 are also: (a) that the three N-atoms are pyramidal (and thus centers of chirality), (b) that the five-membered heterocycle takes on a twist (half-chair) form, and (c) that the regioselectivity of the cycloaddition places the (E)-substituent of the olefine 2 vicinal to the terminal (Z)-substituent of the azimine 1 . On this basis the constitutions of 6 and 7 are assigned. The spectral properties of the triazolidines 5, 6 and 7 , including the ¹⁵N-NMR signals of one example, are compared with those of the related triazane 12 .     

Photoinduzierte 1, 3-dipolare Cycloaddition von 3-Phenyl-2H-azirinen an Azodicarbonsäure-diäthylester. 32. Mitteilung über Photoreaktionen

Irradiation of 2, 2-dimethyl-3-phenyl- ( 1a ), 2, 3-diphenyl-2H-azirine ( 1b ) or the azirine-precursors 1-azido-1-phenyl-propene ( 2a ) and 1-azido-1-phenyl-ethylene ( 2b ), respectively, in benzene in the presence of azodicarboxylic acid diethylester, yields the corresponding 1, 2-carbethoxy-3-phenyl-Δ³-1, 2, 4-triazolines 4a–d (Scheme 1). Refluxing 4 ( a, c or d ) in 0, 2–0, 4M aqueous ethanolic potassium hydroxide leads to the formation of the 1-carbethoxy-3-phenyl-Δ²-1, 2, 4-triazolines 6 ( a, c or d ). Under the same conditions 4b is converted to 3, 5-diphenyl-1, 2, 4-triazole ( 7b , Scheme 2). In 10M aqueous potassium hydroxide solution heating of either 4 ( c or d ) or 6 ( c or d ) yields the 3-phenyl-1, 2, 4-triazoles 7 ( c or d ). Photolysis of 1-carbethoxy-5, 5-dimethyl-3-phenyl-Δ²-1, 2, 4-triazoline ( 6a ) in benzene in the presence of oxygen and trifluoroacetic acid methylester gives the 5-methoxy-2, 2-dimethyl-4-phenyl-5-trifluoromethyl-3-oxazoline ( 13 , Scheme 5). 5, 5-Dimethyl-3-phenyl-1, 2, 4-triazole seems to be the intermediate, which on losing nitrogen gives the benzonitrile-isopropylide ( 3a ).     

Ringerweiterungen und Ringverengungen bei der Umsetzung von 1, 3-Oxazolidin-2, 4-dionen und 1, 3-Thiazoiidin-2, 4-dion mit 3-Amino-2H-azirinen

Ring Enlargements and Ring Contractions in the Reaction of 1, 3-Oxazolidine-2, 4-diones and l, 3-Thiazolidine-2, 4-dione with 3-Amino-2H-azirines The reaction of 3-amino-2H-azirines 1 and 1, 3-oxazolidine-2, 4-diones 2 in MeCN at room temperature leads to 3, 4-dihydro-3-(2-hydroxyacetyl)-2H-imidazol-2-ones 3 in good yield (Scheme 2, Table 1). A reaction mechanism proceeding via ring enlargement of the bicyclic zwitterion A to give B, followed by transannular ring contraction to C, is proposed for the formation of 3 . This mechanism is in accordance with the result of the reaction of 2a and the ¹⁵N-labelled 1a *: in the isolated product 3a *, only N(3) is labelled (Scheme 1). The analogous reaction of 1 and 1, 3-thiazolidine-2, 4-dione ( 5 ) is more complex (Schemes 4 and 5, Table 2). Besides the expected 3, 4-dihydro-3-(2-mercaptoacetyl)-2H-imidazol-2-ones 7, 5-amino-3, 4-dihydro-2H-imidazol-2-ones of type 8 and/or N-(1, 4-thiazin-2-ylidene)ureas 9 are formed. In the case of 2-(dimethylamino)-1-azaspiro[2. 3]hex-1-ene ( 1d ), the postulated eight-membered intermediate 6d could be isolated. Its structure as well as that of 9f has been determined by X-ray structure analysis. A reaction mechanism for the formation of the 1, 4-thiazine derivatives of type 9 is proposed in Scheme 6.     

Heterolytische Anlagerungen an Acetylen-Verbindungen, 2. Mitt.: Einwirkung von N-Bromsuccinimid auf 4-Phenyl-3-butin-1-ol oder 3-Phenyl-2-propin-1-ol in Essigsäure

Zusammenfassung Im Gegensatz zu anderen Acetylen-Verbindungen reagiert 4-Phenyl-3-butin-1-ol mit N-Bromsuccinimid in Eisessig bei Raumtemp. zu einem Gleichgewichts-Gemisch von 3,3-Dibrom-3-benzoylpropanol und dessen cyclischem Tautomeren (2-Phenyl-2-hydroxy-3,3-dibrom-tetrahydrofuran), das auch durch Anlagerung von unterbromiger Säure an denselben Acetylen-Alkohol herzustellen ist. Es wird vermutet, daß das entsprechende Dibrom-diacetoxy-derivat als Zwischenprodukt entsteht. 3-Phenyl-2-propin-1-ol reagiert mit N-Bromsuccinimid in Essigsäure nur in Gegenwart von Wasser zu 2,2-Dibrom-2-benzoyläthanol. Die Umsetzung von Acetylen-Verbindungen mit N-Bromsuccinimid in Essigsäure ist eine bequeme Methode zur Herstellung von ,-Dibromketonen, wobei vorhandene OH-Gruppen nicht angegriffen werden.

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Unlike many other acetylenic compounds, 4-phenyl-3-butin-1-ol reacts at room temperature with N-bromosuccinimide in anhydrous acetic acid, yielding an equilibrium mixture of 3,3-dibromo-3-benzoyl-propanol and its cyclic tautomere, 2-phenyl-2-hydroxy-3,3-dibromo-tetrahydrofuran. The same product is obtained also by addition of HOBr to the acetylenic alcohol mentioned above. An assumption is made that the corresponding dibromodiacetoxy derivative is involved as an intermediate in the reaction with N-bromosuccinimide. 3-Phenyl-2-propin-1-ol interacts with N-bromosuccinimide and acetic acid in presence of water only, giving 2,2-dibromo-2-benzoyl-ethanol. The reaction with N-bromosuccinimide is a convenient method for synthesis of ,-dibromo-ketones from acetylenic compounds, preserving unchanged the hydroxyl groups.

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Mit 2 Abbildungen

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Siehe Internationales Symposium über Konstitution und Reaktions-fähigkeit organischer Verbindungen, Sofia, 21. bis 24. Juni 1966.     

Untersuchungen von Reaktionsmechanismen durch Isotopenmarkierung,VII. Zum Mechanismus der Ringverengung von 2,2-Dichlor-6-methyl-4H-1-thiochroman-3,4-dion

It is shown by use of¹⁴C-labeling that the ring contraction reaction of 2,2-dichloro-6-methyl-4H-1-thiochroman-3,4-dione (1) leads to elimination of C-2 as CO₂. Formation of the 5-methyl-2,3-dihydrobenzo[b]thiophen-2,3-dione (2) is suggested to proceed via hydrolytic opening of the thiolactone-binding in1. recyclisation and subsequent oxidation by unreacted1.

Herrn emer. Univ. Prof. Dr.E. Ziegler zur Vollendung seines 70. Lebensjahres mit besten Wünschen gewidmet.     

Die 1,3-dipolare Cycloaddition von Acetylendicarbonsäure-estern an 2-Methyl-4-phenyl-chinazolin-3-oxid

The 1,3-dipolar addition of acetylenedicarboxylic esters (IX and X) to 2-methyl-4-phenyl-quinazoline 3-oxide (VIII) in benzene/methanol and benzene/ethanol, respectively, gives the esters XI and XII of 3-amino-3-phenyl-2-(2-acetamidophenyl)-acrylic acid as main products and the esters XIII and XIV of 2-methyl-4-phenyl-5H-benzo[d][1,3]diazepin-5-carboxylic acid as by-products. The constitutions of XI and XII are elucidated by acid hydrolysis to the 2-phenylindole-3-carboxylic esters VI and VII, respectively, and by ozonolysis of XII to give benzamide and ethyl o-acetamido-mandelate (IV). The alkaline hydrolysis of XI or XII gives the enamine derivative XVIII, which is hydrolysed by acid to oxindole and benzoic acid. The structure elucidation of XIII and XIV is based on spectroscopic data together with thc formation of XV by alkaline hydrolysis. Mechanisms arc proposed for the reaction paths.     

Spirocyclische 3-Oxazoline durch 1,3-dipolare Cycloaddition von Benzonitrilio-2-propanid mit 1,4-Chinonen

Spiro 3-Oxazolines from the 1,3-Dipolar Cycloaddition of Benzonitrilio-2-propanide and 1,4-Quinones On irradiation with light of wavelength 290–350 nm, 2,2-dimethyl-3-phenyl-2H-azirine (1b) reacts with 1,4-naphthoquinone to give the 1H-benzo [f]isoindol-4,9-dione (11) (Scheme 3) via cycloaddition of the benzonitrilio-2-propanide (2b) onto the quinone C, C-double bond. With 2-methyl- and 2,3-dimethyl-1,4-naphthoquinone, the nitrile ylide 2b undergoes cycloaddition preferentially onto the C, O-double bond of the quinone, leading to spiro-oxazolines 12 and 14 (Scheme 4). Steric as well as electronic effects can be discussed to explain the observed site selectivity of the cycloaddition. With the 1,4-benzoquinones 15a, 15b, 15d and 15f , nitrile ylide 2b undergoes the 1,3-dipolar cycloaddition exclusively onto the C, O-double bond. The corresponding spiro-oxazolines have been isolated in 17–32% yield. This contrasts with the previously reported results with benzonitrilipo-phenylmethanide (2a) , which undergoes cycloaddition to the C, C-double bond of 1,4-benzoquinones (cf. [1]). This difference in the site selectivity of the 1,3-dipolar cycloaddition can be explained with Houk's concept of LUMO-polarization, that is, the stronger nucleophilic dipol 2b polarizes the LUMO of a α,β-unsaturated carbonyl compound more efficient than the less nucleophilic 2a. This leads to a preference of the cycloaddition to the C, O-double bond in the case of 2b. With 2,3-dimethyl- (15c) and 2,3,5,6-tetramethyl-1,4-benzoquinone (15e) , nitrile ylide 2b undergoes C, O- as well as C, C-cycloaddition (Schemes 7 and 8).     

[3+2] Cycloaddition nach addition von allylalkohol und allylaminen an 5-diazourazile

The non-isolable allylalcohol adduct 2c of 5-diazouracil 1 undergoes intramolecular [3+2] cycloaddition to afford the tricyclic pyrazolofuropyrimidine 3 . In a similar way the reaction of the 5-diazouracils 2 , 2a and 2d with allylamine and diallylamine proceeds via the 6-amino-adducts to provide the tricyclic pyrazolopyrrolopyrimidines 5 , 5a , 7 and 7a . With allylamine and 2a , the 1,2,3-triazolederivative 6 is obtained as a byproduct.     

Chelate von β-Dicarbonylverbindungen und ihren Derivaten. 48 Ligandeigenschaften von 1-Phenyl-3-methyl-4-thiobenzoylpyrazolon, -4-benzoylthiopyrazolon und -4-benzoylselenopyrazolon

Chelates of β-Dicarbonyl Compounds and their Derivatives. 48. Properties of the 1-Phenyl-3-methyl-4-thiobenzoylpyrazolone, -4-benzoylthiopyrazolone, and -4-benzoylselenopyrazolone Ligands Thio and seleno derivatives of 1-phenyl-3-methyl-4-benzoyl-pyrazolone were synthesized by reaction of 1-phenyl-3-methyl-pyrazolon with dithiobenzoic ester and by reaction of the analogue 4-benzoyl-5-chlorpyrazole with sodium hydrosulfide or -selenide. Metal chelates of Cu, Ni, Co, Zn, Cd, Hg, Tl, and In were isolated. The influence of the central atoms on the optical behaviour was studied.     

Untersuchungen an diazoverbindungen und aziden—LVII: Tri- und tetracyclen aus 5-(diazomethyl)-5h- benzocycloheptenen und 4-phenyl-1,2,4-triazolin-3,5-dion

The phosphoryl diazomethanes 10a and b undergo electrophilic diazoalkane substitution with the 7-alkylthio benzocycloheptenylium perchlorates 9a andb to the 5-(diazomethyl-5H-benzocycloheptenes 11a–11d. Even the non-dissociated 7 is suited for such a substitution process, as is shown by the reaction with 13 to give 14. Thediazo compounds 11a–11d such as 14 and 17 react with 4-phenyl-1,2,4-triazolin-3,5-dione(PTAD, 2) presumably via the betaines 18 to the cyclo-adducts 19a–19f, in which the diazo function remains unchanged. In contrast the 5-(diazomethyl)-5H-benzocycloheptens 20a–20d with 2 yield the tetracycles 23a–23d under loss of nitrogen ; for 23c an X-ray structure analysis was performed. We assume that the reaction proceeds via dipole like intermediates (21,22,24).     

Synthese von 1, 3, 4-Oxadiazolen und 4, 5-Dihydro-1, 2, 4-triazinen aus 3-Dimethylamino-2, 2-dimethyl-2 H-azirin und Carbohydraziden

Synthesis of 1,3,4-Oxadiazoles and 4,5-Dihydro-l,2,4-triazines from 3-Dimethylamino-2,2-dimethyl-2 Hazirine and Carbohydrazides 3-Dimethylamino-2, 2-dimethyl-2 H-azirine ( 1 ) reacts with aromatic carbohydrazides to give 2-(1-amino-1-methylethyl)-5-aryl-1, 3, 4-oxadiazoles ( 7 , 10 , 11 ). With ethyl carbazate the azirine 1 forms the aminoester 15 , which is easily cyclized to the 4, 5-dihydro-1, 2, 4-triazin-3 (2H)-one 16 . From the reaction of 1 with oxamohydrazide ( 17 ) and oxalodihydrazide 19 the 4, 5-dihydro-1, 2, 4-triazin-3-carboxamide 18 and the symmetric compound 20 , respectively, have been isolated. Reactions supporting the structures of the new compounds are described.