Pschorr synthesis

Intramolecular arylations can also be carried out photochemically. Huisgen and Zahler (1963 a) prepared fluoren-9-one by irradiation of benzophenone-diazonium salts in dilute sulfuric acid. The classical Pschorr synthesis of phenanthrene-9-carb-... 

It is therefore not astonishing that in the Gomberg-Bachmann reaction, the intermolec-ular counterpart of the Pschorr synthesis, yields are generally low. The homolytic part of the Gomberg-Bachmann reaction is, in the opinion of March142 and of the present author, not sufficiently well understood on the basis of the experimental data. Galli117a does not discuss this problem in his review. 

Polyhalo ketones, reductive dehalogenation of, 29, 2 Pomeranz-Fritsch reaction, 6, 4 Prevost reaction, 9, 5 Pschorr synthesis, 2, 6 9, 7 Pnmmerer reaction, 40, 3 Pyrazolines, intermediates in diazoacetic ester reactions, 18, 3 Pyridininm chlorochromate, 53, 1 Pyrolysis ... 

Although the synthesis of 6,7-dihydrobenzo[a]quinolizinium salts was claimed (52YZ1273) many years ago, it was later shown (59CPB609) that the early report was in error. The first synthesis of the 6,7-dihydro derivative was finally accomplished by Akaboshi and Kato (63YZ1067) by a modification of the Pschorr synthesis (Scheme 93). The necessary amine... 

Pschorr Synthesis. In this synthesis of phenanthrene derivatives, one of the steps involves the union of two aryl nuclei through a diazotiza-tion reaction. By treatment of diazotized a-phenyl-o-aminocinnamic add with copper, 9-phenanthroic add is obtained.24... 

A careful reexamination of the Pschorr synthesis has shown that, in the copper-catalyzed reaction, products are formed which are not found when the diazonium salt is decomposed thermally. Thus, in a typical example, the fluoroborate (92) of o-amino-A-methylbenzanilide forms both the spirocyclohexadienone (93) and the spirohexadiene dimer (94) as well as A-methylphenanthridone, and the proposed... 

DeLos F. DeTar, The Pschorr Synthesis and Related Diazonium Ring Closure Reactions, Org. React. 1957, 9, 409 162. 

In the Pschorr synthesis (Scheme 12.12), a Perkin reaction (see Chapter 6) between 2-nitrobenzaldehyde and sodium phenylacetate in the presence of acetic anhydride yields 3-(2-nitrophenyl)-2-phenyl-propenoic acid. Reduction of the nitro group and deamination of the resulting amine via its diazonium salt (see Chapter 8) is accompanied by cyclization. Thermal decarboxylation completes the sequence. 

Intramolecular arylation is an important step in the Pschorr synthesis of phenanthrene from cis-o-aminostilbene. ... 

Pschorr synthesis, 267 Purine nucleosides, 143 Pyrazole, 157 Pyrethrins, 191... 

Pschorr synthesis. The Pschorr synthesis of phenanthrene derivatives is usually carried out with copper powder. Australian chemists1 report that a diazotized 2-phenyl-3-(2-aminophenyl)acrylic acid of type (1) undergoes practically instantaneous cyclization in the presence of sodium iodide (acetone is used as solvent). When copper powder is added the Pschorr method requires more than ten hours and the yield is 55%. 

The Pschorr Synthesis and Related Diazonium Ring Closure Reactions ... 

The Gomberg-Batchman-Hey reaction is closely related to the Pschorr synthesis and gives unsymmetrical biaryls by treating aryl... 

The ability of producing a reactive species, either a radical or a cation, from the photochemical denitrogenation of diazonium salts has been used in the photo-Pschorr synthesis as an approach to polycyclic compounds. Thus the irradiation of the diazonium salt 581 affords the azafluorenones 582. ... 

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