Zur Reaktion von Diphenylcyclopropenon mit Guanidinen

Abstract

Eingegangen am 2. Oktober 1980Herrn Prof. Dr. S. Htinig zum 60. Geburtstag gewidmet. Diphenylcyclopropenon (6) reagiert mit 1,1,3,3-Tetraalkylguanidinen (7ad) unter Bildung von 2-Amino-4,5-diphenyl-3H-pyrrol-3-onen 11, die aufgrund ihres spektroskopischen Verhaltens als Cyclomerocyanine charakterisiert werden. Mit Guanidin (7e), 1-alkyl-und 2-phenylsubstituierten Guanidinen (7fh), 1,t-Diphenyl-und 1,2,3-Triphenylguanidin (7i, j) sowie 2-Amino-benzimidazol (36) liefert 6 jedoch ausschliefllich 5,6-Dihydro-5,6-diphenyl-4(1 H)-pyrimidinone (22, 23, 28 -32,33,34,38), deren Konstitution und Konfiguration an C-5/C-6 auf chemischem und spektroskopischem Wege gesichert wird. Ein Mechanismus fur die Bildung der Fiinfring-und Sechsring-Heterocyclen wird diskutiert. On the Reaction of Diphenylcyclopropenone with GuanidinesDiphenylcyclopropenone (6) reacts with 1,1,3,3-tetraalkylguanidines (7ad) forming 2-amino-4,5-diphenyl-3 If-pyrrol-3-ones 11, which are characterized as cyclomerocyanines by their spectroscopic behaviour. With guanidine (7e), I-alkyl-and 1-phenylsubstituted guanidines (7f -h), 1,2-diphenyl, and 1,2,3-triphenylguanidine (74 j) as well as 2-aminobenzimidazole (36) compound 6 yields exclusively 5,6-dihydro-5,6-diphenyl-4(1H)-pyrimidinones (22,23,28 -32,33,34, 38), the constitution and configuration of which at C-5/C-6 is established. A mechanism for the formation of the abovementioned five-and six-membered heterocyclic systems is discussed.Wie in vorangehenden Untersuchungen2-5) gezeigt werden konnte, liegt den Urnsetzungen von acyclischen und cyclischen Iminen 2 und 3 sowie Amidinen 5 mit Diphenyicyclopropenon (6) ein einheitliches Reaktionsprizip zugrunde: Die Azornethinfunktion geht n i t der Cyclopropenon-C,-Einheit eine forrnale [2 + 31-Cycloaddition uber die Dreiringbindung C-1/C-3 ein, wobei der Azomethinstickstoff an C-3 von 6 angreift

Unusual reactivity of thiosemicarbazides towards 2,3-diphenylcyclopropenone: synthesis of new pyridazinethiones and 1,2,4-triazolo[4,3-b]pyridazinethiones

“…We chose thiosemicarbazides 2a-e having various different substituents on the NH in the NH-NH 2 group in order to examine their reactivity, which might affect the course of the reaction (Scheme 1). Elemental analyses and IR, NMR ( 1 H, 13 C, COSY C-H and H-H) and mass spectra were in good agreement with the assigned structures of compounds 3a-c and 4a-c. For example, the IR spectroscopy of the triazolopyridazines 3a gave characteristic triazolo-C=N band at ν = 1610, pyridazine C=C at ν = 1560, and NH and NH 2 absorptions at ν = 3300-3180, and a strong OH absorption appeared at ν = 3450 cm -1 . The IR spectra of compounds 3b,c showed the presence of pyridazine-NH as a sharp strong band between ν = 3280-3200, whereas the OH absorption was noted between ν = 3480-3450 cm -1 .…”

“…The 13 C NMR spectra of 3a-c supported the 1 H NMR spectral data by the appearance of the chiral C-OH at δ = 115.0-115.6, whereas the C=S resonated at δ = 180.6-182.4. Direct one-bond attached hydrogen-carbon correlations were established by 1 H, 13 C-COSY (HETCOR). Accordingly, COSY C-H of compounds 3a and 4a indicated the relation between the phenyl carbons and their protons.…”

“…8 Diphenylcyclopropenone (1) has been found to react with a wide range of imines and other compounds containing the C=N moiety, usually to form azacyclopentenones (pyrrolinones) via formal [2+3] cycloaddition reactions. [9][10][11][12][13][14] By contrast, the reaction of 1 with guanidine and its alkyl and/or aryl derivatives gave the corresponding 5,6-dihydro-4(1H)-pyrimidinone via a formal [3+3] cycloaddition reaction. 15 In general, cyclopropenone is amphiphilic, reacting readily with both nucleophilic and electrophilic reagents.…”

“…Moreover, cyclopropenones are strained ring ambident electrophiles with a tendency to form ring opened products, their reaction with nucleophiles has the possibility of carbonyl or conjugate addition. [9][10][11][12][13][14][15][16][17] Recently, we have found that the reactions of aroylphenylthioureas with 1 in acetic acid afforded the diasteromers of 3-(3 \ -aroyl-1-substituted-thioureido)-2,3-diphenylcinnamic acids. 18 Generally, the N 2 of thiosemicarbazides is described as a softer nucleophilic center than the harder and powerful terminal nitrogen N 1 .…”

12-Phenyl-5,12-dihydrodibenz[b,g]azocin-5-one, C21H15NO

“…Our former results in studying synthesis, structural properties and chemical behaviour of cyclocyanines (Eicher, Abdesaken, Franke & Weber, 1975;Eicher & Franke, 1981) prompted us to direct synthetic efforts to the class of eight-membered cyclic merocyanines (1), especially with regard to the aspect of a probable participation of a resonance hybrid A~-,B in the ground-state description of the 1,4-dihydroazocin-4-one system (1).…”