The photoreaction of naphthalene with pyrrole; products and reaction mechanism

Abstract

514, Washington, 1951. b The effects of these solvents are probably due in part to their hydrogen bonding properties.Given by [(II)/(II) + (111)] x 100; minor products were present in all runs, total 14%. hydro-l-naphthy1)pyrrole (11) and 2-( 1,2-dihydro-2-naphthy1)pyrrole (III).6 The progress of the reaction and the ratios of products were monitored by g.l.c., and compounds ( 11) and (111) were isolated by chromato-

Friedel–Crafts Ring-Coupling Reactions Promoted by Tungsten Dearomatization Agent

“…η 2 -Coordination of naphthalene with the TpW(NO)(PMe 3 ) metal fragment allows for selective protonation at the 1-position, followed by nucleophilic addition to the 2-position. Of the organic complexes made through this strategy, only 38 has been previously synthesized: under photochemical conditions, pyrrole and naphthalene are reported to combine to produce 38 as one component of a complex mixture of products …”

Photochemical transformations of 2,2′-(1,2-phenylenedivinylene)dipyrroles

“…In the presence of triethylamine an electron transfer from triethylamine to 4a occurs forming the anion radical of 4a (15). This is evident from the influence of solvent polarity on the course of photochemical reaction, where the reaction is hardly possible in solvents of lower polarity than acetonitrile.…”

“…3,8,9,11 Thus, upon irradiation of styrylpyrroles (1b and 1c, Scheme 1) intermolecular regiospecific addition to the double bond occurs giving the mixture of dimeric products 3a and 3b, respectively. 3 The mechanism of the reaction is rationalized by an electron transfer followed by a proton transfer and radical recombination, analogues to the photochemical addition of pyrrole to benzene, 12,13 naphthalene, 14, 15 and stilbene. [16][17][18] In order to obtain [3.2.1] bicyclic systems from pyrrole, in analogy to photoproduct 2a obtained in high yield from 1a, we substituted the pyrrole nitrogen with a methyl group in order to prevent the transfer of the hydrogen (NH transfer).…”

Photoaddition reaction of 1,2-dialkyl-indoles and -pyrroles to 1-methyl-2-pyridone via proton transfer from the 2-methylene group of the indole or pyrrole

“…NH group is essential to the photoaddition reaction because it acts as a proton source in the proton transfer process, which is similar to the photoaddition reaction of pyrrole to benzene2 and naphthalene. 3 We report here the photoaddition reaction of 1,2-dialkyl-indole 2-5 and -pyrrole derivatives 6, 7 to 1-methyl-2-pyridone 1, in which the methylene (or methyl) group at the 2-position of the indole and the pyrrole ring acts as a proton source instead of the NH group. The photoreactions were performed on degassed dioxane or acetonitrile solutions of the n-excessive heterocycles (1 .O mol dm-3) and 1 (0.05 mol dm-3) by external irradiation with a 400 W high-pressure mercury lamp through a Pyrex filter for 15 h at ambient temperature.…”