Tetrachloro intermediates

Mizutani and coworkers57a confirmed the presence of polychloro(methylsulfonyl)biphenyls (159-170) as sulfur-containing metabolites of chlorobiphenyls (Cl-BP) in the feces of mice based on both GLC-mass spectrometry and chemical derivatization. In some cases comparison with authentic samples (161 and 162) was also made. When preparing 161 and 162,2,5-dichloro-3-(methylsulfonyl)aniline, 2,5-dichloro-l-iodo-3-(methylsulfonyl)benzene and 2,2, 5,5 -tetrachloro-3,3 -bis(methyl-sulfonyl)biphenyl were also obtained and their four peak El mass spectra reported572. Similar data were given for the corresponding 4-substituted intermediates, which were involved in the preparation of 162. Also 2,4, 5-trichloro-2 -(methylsulfonyl)-biphenyl was prepared and its four peak mass spectra given. Metabolites 163 and 164 were also identified by comparison with the authentic standards. 

The most efficient synthesis is based on the reaction of phthalic anhydride with the sodium salt of the pyrrole the intermediate acid after cyclization generally provides high yields of 206 and/or its substituted derivatives. Tetrachloro derivative 212 was prepared from tetrachlo-rophthalic anhydride via acid 211 by this procedure [90JCS(P 1) 1463 ]. 

The reactivity of stable germaphosphenes has been previously investigated and reviewed.3,4,7 The chemical behavior of Mes2Ge = PAr 155 toward orthoquinones (tetrachloro-o-benzoquinone, 3,5-di-terr-butyl-o-benzoqui-none, and 1,2-naphthoquinone) and ce-diketones (benzil and biacetyl) has been examined. The reaction with o-quinones involved probably radical intermediates, and in each case only the less encumbered isomer of the corresponding [2 + 4] cycloadduct 156 was formed. Benzil led in a very similar manner to a l,4,2,3-dioxagermaphosphin-5-ene 157, whereas, as was observed with acetone, an ene-reaction occurred with biacetyl to afford 158138 (Scheme 29). 

Furans also undergo cycloadditions with o-benzoquinones. Thus furan, 2-methylfuran, 2,5-diphenylfuran and benzo[ >]furan yield dihydrofurobenzodioxins of type (238) with tetrachloro-l,2-benzoquinone (Scheme 83). The reaction of furan with 1,2-benzoquinone affords only a 1% yield of adduct because most of the quinone undergoes polymerization. The reaction with 2-methylfuran produces a 25% yield of adduct, however. The reactions are thought to involve the electrophilic attack of the quinone on the furan to produce a carbonium ion. In the case of 2-methylfuran the more stable carbonium ion (239) is produced. Evidence for a two-step mechanism is the diversion of the intermediate (239) to the addition product (240) which may be isolated when the reaction is conducted in the presence of ethanol (69JCS(C)1694). 

Some reactions of munchnones occur via acylamino ketenes, the covalent valence tautomers of the betaines. The ketenes are intermediates in the thermolysis (see Scheme 22) and in the formation of azetidinones from imines (equation 69) they are thought to be involved in the aminolysis of the mesoionic compounds, which results in amides of a-acylamino acids, and in the formation of the benzodioxin (247) by the combined action of acetic anhydride and tetrachloro-o-benzoquinone on Af-benzoylalanine (equation 70). 

Peroxidase transformation of mono- and dichlorinated anilines have been extensively studied, but there is scarce information about highly halogenated anilines. From several peroxidases tested, only chloroperoxidase from C.fumago was able to transform highly chlorinated anilines [69]. This first report on peroxidase transformation of pentachloroaniline showed that the main product is a polymeric material, and pentachlorophenol and tetrachloro-l,4-benzoquinone are also produced (Fig. 8.3). The mechanism of pentachlorophenol production from pentachloroaniline is still unknown. However, the tetrachloro-l,4-benzoquinone seems to be a product of the pentachlorophenol intermediate and not produced directly from the pentachloroaniline as found in pentachlorophenol peroxidase transformation [69]. The identified products from the chloroperoxidase-mediated transformation of tetrachloroaniline are the polymer, which represented 87-95% of the total mass, pentachloroaniline, and three different dimers, which have been identified as minor products [69]. 

Rhenium displays an unusual array of oxidation states and coordination numbers that make it the subject of much current research. The following preparation, adapted from one developed by Chatt and coworkers, provides a convenient synthesis of trichlorooxobis(triphenylphosphine)rhenium(V)1 based on either rhenium(VII) oxide or perrhenate salts. The trichlorooxo compound is a versatile intermediate for the synthesis of other rhenium complexes such as wer-trichlorotris(dimethylphenylphosphine)rhenium-(III),2 as described below. The rhenium(III) complex, in turn, provides a starting point for synthesis of other compounds such as frans-tetrachloro-bis(dimethylphenylphosphine)rhenium(IV)3 and tris(dimethylphenylphos-phinepentahydrido)rhenium(V).4 An alternative synthesis of the trichloro-complex is described in the accompanying preparation by Douglas and Shaw.4... 

Oxathiacrown ethers containing a diene unit 40 and 41 were prepared by the reaction of l,3,5,5-tetrachloro-2-nitrobutadiene derivatives with bis(2-mercaptoethyl) ether (Scheme 7) <2002PS2529>. The authors reported that 40 formed by the cyclization of an intermediate (Cl2C=CCl-C(N02)=C(SR)-S-(CH2)2-0-(CH2)2-S-Na+). Compound 41 was prepared by the cyclization of the intermediate (Na+S-(CH2)2-0-(CH2)2-S-ClC=CCl-C(N02)2=C(SR)-S(CH2)2-0-(CH2)2-S Na+ or Cl2C=CCl-C(N02)2=C(SR)-S(CH2)2-0-(CH2)2-S-S-(CH2)2-0-(CH2)2-S Na+), which were obtained by the reaction of l,3,5,5-tetrachloro-2-nitrobutadiene derivatives with bis(2-mercaptoethyl) ether. In this report, the E/Z stereochemistry of these compounds was not reported. 

Thus, it might be possible to observe intermediate 72 by irradiating at low temperature. This result has been obtained in preliminary studies55> although results have not been nearly so clear-cut as might be desired. Compound 73, which is converted quantitatively into l,2,3,4-tetrachloro-5,6-diphenylbenzene (76) upon irradiation in the visible at room temperature, was irradiated in a glass at 436 nm and 77 K. A new... 

Wilkinson and Schroeder (1979) have shown that the triplet states of aromatic hydrocarbons are quenched by quinones, the efficiency of quenching being related to the electron affinity of the quinone and the ionisation potential of the triplet hydrocarbon (Schroeder and Wilkinson, 1979). It was concluded that the quenching did not involve full electron transfer in nonpolar solvents. Photolysis experiments have shown that in propionitrile tetrachloro-benzo-l,4-quinone reacts with naphthalene to give radical ions (Gschwind and Haselbach, 1979). The naphthalene radical cation reacts with naphthalene to give a detectable intermediate. 

ReCle] " is photooxidized by electron acceptors, for example, 2,3,5,6-tetrachloro-l,4-benzoquinone (chloraml) and DDQ, to [ReCle], which is an intermediate in the oxidation of Cl to CI2 and of toluene to benzaldehyde. ... 

Anomeric ediyl hemiacetals of the methyl ester of aldehydo-D-galacturonic acid tetraacetate were prepared by Dimler and Link. In chloroform, these isomers mutarotated to an intermediate value over a period of several hours, and the mutarotation was complex. Solvent-free oldehydo-D-galactose pentaacetate was obtained in crystalline form, and did not show mutarotation in 1,1,2,2-tetrachloro-ethane. " In the presence of water, the corresponding crystalline aldehydrols of aZde/tydo-D-galactose pentaacetate and aldehydo-T>-mannose pentaacetate were obtained. 

Under oxidative conditions, both alkyl and aryl aldehydes condense, giving the 2-alkyl- or 2-aryladenine derivatives.Oxidation of the dihydro intermediate, which is not isolated, is effected either atmospherically, with oxygen and palladium in methanol, or by treatment with tetrachloro-l,4-benzoquinone (chloranil) in dimethylformamide, e.g. formation of 3. ... 

Treatment of 2,2,4,4-tetrachloro-l,3-dithietane with aniline is said to give 2- N-phenylimino)-4,4-dichloro-l,3-dithietane. ° An A-methylimino-l,3-dithietane was suggested as an intermediate in the reaction of bis-trifluoromethylthioketene with methyl isothiocyanate. 2-A A-Dialkylamino-l,3-dithietan-2-ylium salts are obtained by treatment of A, A-dialkyldithiocarbamates with protons or dimethyl sulfate as exemplified by the synthesis of 555 and 556, respectively. ... 

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