Reaktionen von Halogen‐aminomethylen‐2H‐pyrrolen und Halogen‐pyrrolaldehyden

Abstract

Die Halogen-aminomethylen-2H-pyrrole konnen einem Basenaustausch, z. B. unter Bilduug von 1, unterworfen werden. Durch Umsetzung mit S-Verbindungen gewinnt man die Thioather 3 und 4, mit Pyrrolinonen die Halogen-neodipyrromethene 5 und mit CH-aciden Substanzen als weitere Kondensationsprodukte 6 und 7. -1-Substituierte Halogen-formyl-pyrrole dienen zur Synthese von N-substituierten Neodipyrromethenen, wie 8, das mit Kaliumacetat zu dem neuartigen Propentdyopent-Addukt 9 fuhrt. Brom-formyl-pyrrol bildet das Tripyrren 10, das mit Kaliumacetat in das Dioxo-tripyrren 11 iibergefuhrt wird. Reactions of Halogeno-aminomethylene-2H-pyrroles and Halogenopyrrole AldehydesHalogeno-aminomethylene-2H-pyrroles undergo base exchange to form e. g. 1. By reaction with sulfur compounds, the thioethers3 and4 are formed; with pyrrolinones, the halogenoneodipyrrometheues 5; and with CH-acidic substances, the condensation products 6 and 7 are obtained. -1-Substituted halogeno-formylpyrroles are utilised to synthesize N-substituted halogenoneodipyrromethenes, e. g. 8, which is transformed with potassium acetate into the new propentdyopent-adduct 9. Bromo-formylpyrrole forms the tripyrrene 10, which gives with potassium acetate the dioxotripyrrene 11. Die in der voranstehenden Arbeit 1) beschriebenen 1 Hund 2H-Pyrrole lassen sich in mannigfacher Weise zu ein-und mehrkernigen Pyrrol-Verbindungen umsetzen. Reaktionen der Halogen-aminomethylen-2H-pyrroleDie vielfaltigen Reaktionsmoglichkeiten der Mannich-Gruppierung eroffnen ein weites Feld fur die Darstellung neuer Pyrrol-Derivate aus den cd-unsubstituierten a-Pyrrol-Mannichbasen.2-Dimethylaminomethyl-pyrrol ist schon Basenaustauschreaktionen unterworfen worden 2-31.

Hydroxy- and Aminopyrroles and Related Compounds

“…SPh substitution on an intermediate iodopyrrole, (178) but that the unstable species ArSI is probably involved in an electrophilic substitution reaction. This mechanism has a close analogy with the oxidative coupling of thiourea with pyrrole in the presence of iodine in which pyrryl isothiouronium salts are formed (see Chapter 4, Section D).…”

Azafulvenes

“…(8 · 9) In the absence of a 6-phenyl group, the stability of the azafulvene system appears to be extremely low. (20) Nucleophilic attack at the 6-position of (All) by pyrrolin-2-ones in the presence of sodium methoxide leads to the elimination of the 6-dimethylamino group and the formation of (A15). the formation of a similar dimeric product through the acid-catalyzed reaction of 2,5-dimethylpyrrole with benzaldehyde (14) ).…”

“…The 1-protonated salts of (Al) (X = NMe 2 ) are intermediates of the Vilsmeier-Haack formylation of pyrrole (see p. 152) and, ö although it is possible to observe the formation of the base in solution by neutralization of the salt with triethylamine, any attempt to isolate the base results in 1,3-dipolar dimerization to give the bispyrrolo[l,2-a] [l',2'-c/]pyrazine (A10) (8 13) (cf. (20) The 6-dimethylamino group is also displaced by carbanions to yield 2-pyrrylethenes (A16), (20) whereas A16 R 1 = CN or C0 2 Et reaction of (All) with thiophenol leads to the displacement of both the 6-dimethylamino and the 2-halogeno groups, possibly through the formation of a 6-thiophenyl-l-azafulvene, which is hydrolyzed to (A 17) under the work-up conditions. The isolation of the 2-halogeno-3,4-dialkyl derivative (All) (X = Cl or Br; R = alkyl), and of 2,3-dichloro-4-(3-chloro-2-nitrophenyl)-6-dimethylamino-1-azafulvene, however, has been reported.…”

“…the formation of a similar dimeric product through the acid-catalyzed reaction of 2,5-dimethylpyrrole with benzaldehyde (14) ). (20 (15_17) Catalytic reduction of (Al) (X = NMe 2 ) yields 2-(/V,N-dimethylamino)pyrrole (A12) (R = H), and, under basic conditions, the analogous reduction of (All) results in the concomitant elimination of the halogen.…”

Reactivity of pyrrol-2-ones. (review)

“…Condensation of 4-methyl-5-tosyl-3-(2-tosyl)-5H-pyrrol-2-one with 5-tert-butoxycarbonyl-4-(2-methoxycarbonylethyl)-3-methylpyrrole in the presence of a catalyst gave compound 83, which is a potential equivalent to the C/D-ring component of phytochromobilin, with a yield of 73%. The pyrromethene structures based on pyrrol-2-ones were studied in a series of papers [50,[114][115][116][117][118][119]. Pyrrol-2-ones are also intermediates or final compounds in the synthesis of biologically active materials [1, 5,6,[120][121][122][123][124][125][126][127][128][129][130][131].…”