2- Hydroxy-2’ biphenyl

By analogy, thermal cyclization was described also for 6-nitro-2 -hydroxy-biphenyl-2-carboxylic acids, e.g. 14, obtained by other methods. The same product 15 was also formed from lactone 17, prepared by oxidation of fluorenone 16 (Scheme 2). If the reaction was performed in DMF, the corresponding dimethylamide was isolated (82KGS703, 86KGS852, 87KGS314, 89MI1). 

Biological. Reported biodegradation products include 2,3-dihydro-2,3-dihydroxybiphenyl, 2,3-dihydroxybiphenyl, 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate, 2-hydroxy-3-phenyl-6-oxohexa-2,4-dienoate, 2-oxopenta-4-enoate, phenylpyruvic acid (quoted, Verschueren, 1983), 2-hydroxy-biphenyl, 4-hydroxybiphenyl, and 4,4 -dihydroxybiphenyl (Smith and Rosazza, 1974). The microbe Candida lipolytica degraded biphenyl into the following products 2-, 3-, and 4-hydroxy-biphenyl, 4,4 -dihydroxybiphenyl, and 3-methoxy-4-hydroxybiphenyl (Cerniglia and Crow, 1981). 

The dissolving metal reduction of benzo[b]furans and dibenzofurans is a classical technique and, depending on the conditions, can give rise to a variety of products.Several examples are summarized in equations (104-108). " The cleavage of dibenzofurans to afford 2-hydroxy biphenyls (equation 107) is a particularly valuable route to these compounds. The reduction of 3-carbomethoxybenzofu-rans with Mg/MeOH (equation 108) is reminiscent of the indole reduction reported earlier (equation 51). 

Under treatment with phenyl sodium, diphenyl ether (224) affords 57% of 2-hydroxy-biphenyl (225) (equation 153) . Equation 154 outlines the mechanistic course of this reaction. The first step is the abstraction of an ortto-hydrogen to the oxygen to afford... 

Successive oxidation at the sulfur atom occurs with formation of the sulfoxide followed by elimination of sulfite to yield either 2-hydroxy-biphenyl (Omori et al. 1992) or benzoate (van Afferden et al. 1990) (Figure 6.54). The pathway for the formation of 2-hydroxybiphenyl... 

Butyl-2-hydroxy-5-methyl-benzaldehyds 3-Formyl-2-hydroxy-biphenyl... 

Additional lack of chain flexibility is introduced in the polyphosphazene skeleton when polyspirophosphazenes are considered. These materials are obtained by reacting 2,2 -di-hydroxy biphenyl or l,r-binaphthyl derivatives with polydichlorophosphazene [305], leading to the formation of polymers having the structure shown in Formula below. 

Diazotiertes 4-Fluor-anilin reagiert mit Salicylsaurc problemlos zu 3-Carboxy-4 -fluor-4-hydroxy-azobenzol (75% Schmp. 218-220°), das sich mit Tris-[triphenylphosphan]-rhodiumchlorid zum entziindungshemmenden 3-Carboxy-4-fluor-4-hydroxy-biphenyl zersetzen laflt1 ... 

When biphenyl is either chlorinated or brominated in the presence of iron(III) or antimony(V)chloride, 2- and 4-halogenated biphenyls are formed. Their hydrolysis, however, requires, strong conditions such as heating in fused potassium/sodium hydroxide with copper at 250-300°. This can cause some isomerization to 3-hydroxy-biphenyl via an aryne mechanism 67). 

Liittringhaus et al. 68) have isolated many interesting substances from the byproducts ( 8%) of the Bayer process. The mechanism has been fully clarified and shown to be an aryne route. When chlorobenzene or diphenylether are treated with sodium phenyl, the products are ortho metalated derivatives and benzyne. These give the same products which are formed in the industrial phenol synthesis. The most interesting compounds are 2- and 4-hydroxy biphenyl, 2,6-diphenyl- and 2,4-diphenyl-phenol l). For similar syntheses see 69). 

Ullmann coupling of 4-iodo-tri-methylsilyl-phenolether by hydroxy-arylation gives 4,4 -hydroxy-biphenyl in 55 % yield 88). 

Kart o Detroit (Ref 4) measured the dissocn constant of 3,5,3, 5 -tetranitro- 4,4 -di hydroxy biphenyl in inethnnol to dotn the effect of NOj groups,ortho, or para to the OH function.on the acidity of the compd... 

P, but a hydroxylated metabolite, 2,2, 6,6 -tetrachloro-4 -hydroxy-biphenyl, competitively bound to estrogen receptor a and produced proliferative responses in the breast cancer assay at concentrations about 10-fold lower than effective concentrations of the parent molecule (Arcaro et al. 1999). 

Waller, C.L., Minor, D.L. and McKinney, J.D. (1995) Using three-dimensional quantitative structure-activity relationships to examine estrogen receptor binding affinities of polychlorinated hydroxy-biphenyls. Environ. Health Persp., 103, 702-707. 

Compound 1 was made from 4-hydroxy biphenyl, which was also an intermediate for an alternate synthesis of bifenazate and the hydroxy-analogs [11]. 

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