Phenanthrene-9-carboxylic acids

An important extension of this carboxylation strategy has recently been suggested by Zhang and Young (1997) who studied the degradation of two polycyclic aromatic hydrocarbons (PAHs), naphthalene and phenanthrene, in a sulfate-reducing sediment. The naphthalene was found to be converted to 2-naphthoic acid and the phenanthrene to phenanthrene carboxylic acid (see below). Further degradation to C02 was rapid after the presumptive initial carboxylation. Possibly carbon dioxide derivatives can be made so electrophilic by enzymatic interactions (shown... 

C,II7CI2F20 38492-84-1) see Halofantrine 13 dichloro-6-(trifluoromethyl)-9-phenanthrene-carboxylic acid... 

Abietic Acid or Sylvie Acid (l,2,3,4,4a,4b,5, 6,10,10a-Decahydro-7-isopropyl-l,4a-dimethyl-1-phenanthrene-carboxylic Acid), C,Hj,COOH,... 

In contrast to the preferred meta mode of intramolecular photoaddition of 5-phenyl-l-pentenes, where the alkene and benzene groups are separated by three atoms, irradiation of the styrene (64) yields a single stereoisomer of the ortho adduct (65). In (64), not only are the reacting units separated by 4 atoms, but also it is the styrene rather than the benzene which is excited. Comparable photoreactivity is seen for phenanthrene-styrene systems such as (66) which yield 2+2 adducts (67) along with products derived from competing Paterno-Btichi reaction of the ester carbonyl with the alkene side chain. The photochemical cycloaddition also proceeds in an intermolecular fashion between the ester of 9-phenanthrene carboxylic acid and para-methoxy-0-methylstyrene. The mechanism of this reaction is shown to involve addition of the styrene to the singlet excited state of the phenanthrene derivative. °... 

The AT-methylanonaine was obtainable by reaction with forniic acid and formaldehyde, and Hofmann degradation via A-methylanonaine methiodide (m.p. 217°) gave a methine base (m.p. 87-90°) and a vinyl-phenanthrene (m.p. 87°) which on oxidation generated a phenanthrene-carboxylic acid (m.p. 240°) which could be decarboxylated to what was evidently 3,4-methylenedioxyphenanthrene (m.p. of picrate, 168°). 

Elimination of sulfur from methyl dibenzo[/),/]thiepin-10-carboxylatcs 15 (R2 = Me) can be achieved in moderate yields (39-55%) upon refluxing in diethyl phthalate in the presence of copper bronze.60 For the dibenzo[A,/]thiepin-10-carboxylic acids 15 (R2 = H), the loss of sulfur is accompanied by decarboxylation. Thus, treatment of these acids with copper bronze in refluxing quinoline for four hours gives the corresponding phenanthrenes 16 (R3 = H) in moderate yield (50%). However, the exposure time to high temperatures influences the product formation. Thus, the decarboxyiated dibenzothiepins are obtained after refluxing for only five minutes.60... 

C[bicarbonate] and mass spectrometry were used to demonstrate the formation of carboxylic acids during the sulfidogenic mineralization of naphthalene and phenanthrene (Zhang and Young 1997). 

Pschorr s synthesis of phenanthrene (1893) in five steps with the essential dediazoniation and ring closure of 2-diazonio-a-phenylcinnamic acid giving, on addition of copper powder, phenanthrene-9-carboxylic acid, is today still the highest yielding one of all the reactions discussed in this section, Pschorr was able to get 93% yield, and today electrochemically induced Pschorr and related reactions141 give almost quantitative yields in several cases. 

Tetramethoxy aristolochic acid (80) was obtained by nitration from the corresponding 3,4,6,7-tetramethoxy-phenanthrene-l-carboxylic acid (81), which was obtained from glaucine (82) via exhaustive Hofmann degradation (twice) followed by oxidation. Catalytic hydrogenation with Pd-C afforded the relevant aristolactam (83) (Scheme 10) (82). 

Cohare and co-workers reported that aristolactam BU (22) was prepared, following Kupchen s method, by Perkin condensation of 6-bromo-3,4-di-methoxy phenyl acetic acid (119) and o-nitrobenzaldehyde (120) (Scheme 14). The 2-bromo-4,5-dimethoxy-2 -nitro-ds-stilbene-a-carboxylic acid (121) was obtained. The nitro group of 121 was reduced with ferrous sulfate and ammonium hydroxide, and the resulting 2-bromo-4,5-dimethoxy-2 -amino-cw-stilbene-a-carboxylic acid (122) without purification was submitted to the Pschorr phenanthrene synthesis to yield l-bromo-3,4-dimethoxyphen-anthrene-lO-carboxylic acid (123). The phenanthrylamine 124 was prepared from 123 via a Schmidt reaction, and, by treatment with n-butyllithium and CO2, 124, afforded 22 (42). 

Djerassi and Engle showed that stoich. RuOyCCl oxidised phenanthrene to 9,10-phenanthrenequinone (Table 3.5) [239], The first catalytic reaction involving RuO was that of pyrene with RuO /aq. Na(IO )/acetone, giving a mixture of pyrene-4,5-quinone, pyrene-1,6-quinone, the lactol of 4-form-ylphenanthrene-5-carboxylic acid (OsOyH O /acetone was more specific, giving pyrene-4,5-quinone) [240],... 

Oxidative photocyclization of stilbene to phenanthrene, which was discovered in 1960, was first applied to the synthesis of [7]helicene by Martin and coworkers in 1967 [26, 44, 45]. This approach was extended to the syntheses of long [njhelicenes (n < 14) and [n]thiahelicenes (n < 15), using both mono- and diannelations. Numerous [nfhelicenes (n < 13) and [n]thiahelicenes (n < 13) were obtained in non-racemic form via the following methods (1) seeded crystallization of conglomerate (e.g. [7]-, [8]- and [9]helicene) [46, 47], (2) resolution by chromatography (e.g. [13]thiahelicene) [48] and (3) photocyclization from a resolved precursor (e.g. [13]helicene from hexahelicene-2-carboxylic acid) [49]. The oxidative photocyclization of stilbenes is still the method of choice for the preparation of selected [n]helicenes and their heteroatom analogs [50-58]. 

Preparation of 8-oxo-8H-5-oxa-l-aza-phenanthrene-6-carboxylic acid ethyl ester... 

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