P-Hydroxy diphenyl

In the colon, sodium picosulphate is converted in to the active comound bis-(p-hydroxy diphenyl) pyridyl methane (BHPM) which stimulates propulsive activity of the colon, prevents absorption of water in the colonic lumen and promotes accumulation of water. 

A small amount of p-hydroxy diphenyl, C6H5.C6H4OH, is formed as the result of the condensation of the diazonium salt with some of the phenol formed in the reaction. The compound can be obtained by filtering the hot solution from which the phenol has been distilled. On cooling, p-hydroxy diphenyl separates out in plates which melt at 164°. 

Chlorinated dibenzo-ip-dioxins were prepared on the gram scale for use as toxicological standards, 2,7-Dichlorodi-henzo-p-dioxin was prepared by catalytic condensation of potassium 2-bromo-4-chlorophenate in 70% yield. Thermal condensation of the potassium salt of 2,4,4 -trichloro-2 -hydroxy diphenyl ether gave a mixture of the 2,8- and 2,7-dichlorodibenzo-p-dioxins which were separated by fractional recrystallization. 2,3,7,8-T etrachlorodibenzo-p-dioxin of 99.9- -% purity was prepared by catalytic condensation of potassium 2,4,5-trichlorophenate. An isomeric mixture of hexachlorodibenzo-p-dioxins was prepared by pyrolytic condensation of sodium 2,3,4,6-tetrachlorophenate. Chlorination of pentachlorophenol (containing < 0.07% tetrachlorophenol) in trichlorobenzene gave octachlorodi-benzo-p-dioxin in 80% yield contaminated by 5-15% heptachlorodibenzo-p-dioxin. Oxidative methods were used to produce octachlorodibenzo-p-dioxin at 99.9% purity. 

The first step in the overall synthetic scheme (Scheme 6) is the condensation of an appropriate carboxylic acid with trifluoroacetaldehyde. The carboxylic acid is chosen to impart specificity for the target enzyme. In one example,[28 the dianion of cyclohexanepropanoic acid (29) was formed by the addition of LDA and then quickly condensed with trifluoroacetaldehyde to form the p-hydroxy acid 30 as a racemic mixture of erythro- and threo-isomers. The p-hydroxy acid 30 is then protected with TBDMSOTf forming 31. Diphenyl phosphorazidate, TEA, and benzyl alcohol were then utilized in a Curtius rearrangement of the protected alcohol 31, which proceeds through an isocyanate intermediate that yields the protected amino alcohol 32 upon reaction with benzyl alcohol. In order for this step to occur at an appreciable rate, a second equivalent of triethylamine had to be added. The amino alcohol 32 was then deprotected and coupled with Boc-Phe-Leu-OH to give the trifluoromethyl alcohol 33, which was oxidized to the corresponding trifluoromethyl ketone 34 as a 1 1.2 mixture of diastereomers using the Dess-Martin periodinane procedure. Thus far, the compound shown in Scheme 6 is the only compound that has been synthesized by this method, but it is reasonable to assume that many other similar fluoro ketones can be produced by this scheme. 

ETHYL P-HYDROXY-P.P-DIPHENYLPROPIONATE (Hydracrylic acid, 3,3-diphenyl, ethyl ester)... 

An alternative approach is to use the readily available P-hydroxy phenyl selenides as Ritter substrates. Amide formation occurs with retention of configuration, indicating that fission of the carbon-oxygen bond is assisted by the neighboring phenylseleno group (Scheme 61). Diphenyl diselenide and iodine react with 1,5-dienes to give carbocyclic products. Initial formation of the episelenonium ion is followed by intramolecular attack and subsequent Ritter reaction (Scheme 62). ... 

Elimination of Ar2CO. p, 3-Diphenyl- 3-hydroxy ketones suffer cleavage to generate Rh enolates, which can he trapped in situ, for example, with RCHO. ... 

Bisphenol A 2,2-Bis (4-Hydroxy-Phenyl) Propane P,P-Dihydroxy- diphenyl- dimethylmethane 4,4-lsopro-pylidenediphenol Ucan Bisphenol Hp ... 

In a study on the potential of a series of substituted trityl groups in oligonucleotide synthesis, the (p-bromophenacyloxyphenyl)diphenyl-methyl group (28) appeared to have several advantages. On account of its size the chloride derived from (28) reacted only with 5 -hydroxy-groups of nucleosides and could easily be removed by the action of zinc and acetic... 

Guided by the success of the Evans and related auxiliaries, several attempts were made to use enantiomerically pure a-bromoacyl oxazolidinones for stereoselective Reformatsky reactions. Fukuzawa and coworkers developed the reaction of various bromoacetyl oxazolidinones 323 as an alternative to an asymmetric acetate aldol addition. The conversion was mediated by samarium iodide and yielded P-hydroxy carbonyl compounds 325 with high diastereoselectivity in optimal combinations of auxiliary group and aldehyde. Among the different auxiliaries, the geminal dimethyl- and diphenyl-substituted ones performed better than the original Evans oxazolidinones. The stereochemical outcome was rationalized by assuming that an O-bound samarium(III) enolate reacts via a chair-like... 

In much the same way, 2,3-diphenyl-6-quinoxalinamine gave 6-(2-hydroxy-naphthalen-l-ylazo)-2,3-diphenylquinoxaline (substrate, 18% HCl NaN02/ HzOt, <5°C, 15 min then solution to p-naphthoI/2.5M NaOH, 30 min 90% analogs likewise)... 

Annual Volume 71 contains 30 checked and edited experimental procedures that illustrate important new synthetic methods or describe the preparation of particularly useful chemicals. This compilation begins with procedures exemplifying three important methods for preparing enantiomerically pure substances by asymmetric catalysis. The preparation of (R)-(-)-METHYL 3-HYDROXYBUTANOATE details the convenient preparation of a BINAP-ruthenium catalyst that is broadly useful for the asymmetric reduction of p-ketoesters. Catalysis of the carbonyl ene reaction by a chiral Lewis acid, in this case a binapthol-derived titanium catalyst, is illustrated in the preparation of METHYL (2R)-2-HYDROXY-4-PHENYL-4-PENTENOATE. The enantiomerically pure diamines, (1 R,2R)-(+)- AND (1S,2S)-(-)-1,2-DIPHENYL-1,2-ETHYLENEDIAMINE, are useful for a variety of asymmetric transformations hydrogenations, Michael additions, osmylations, epoxidations, allylations, aldol condensations and Diels-Alder reactions. Promotion of the Diels-Alder reaction with a diaminoalane derived from the (S,S)-diamine is demonstrated in the synthesis of (1S,endo)-3-(BICYCLO[2.2.1]HEPT-5-EN-2-YLCARBONYL)-2-OXAZOLIDINONE. 

Electrophilic attack on cyclopropenones takes place at carbonyl oxygen, as indicated by the formation of hydroxy cyclopropenium cations on protonation (see p. 28). Hydrogen-bonded complexation between the carbonyl oxygen of diphenyl cyclopropenone and the O-H hydrogen in water212 and substituted acetic acids213 is reported to give rise to well-defined 1 1-adducts (296). 

N-Heteroaromatic compounds like pyridine, pyridazine, pyrazine, isoquinoline, and their derivatives42,250 react with diphenyl cyclopropenone in a formal (3+2) cycloaddition mode to the C=N bond of the heterocycle. As expected from the results discussed earlier (p. 67), the reaction is initiated by attack of nitrogen at the cyclopropenone C3 position and followed by stabilization of the intermediate betaine 390 through nucleophilic interaction of the Cl/C3 bond with the activated a-site of the heterocycle, giving rise to derivatives of 2-hydroxy pyrrocoline 391—394). In some cases, e.g. diphenyl cyclopropenone and pyridine42, further interaction with a second cyclopropenone molecule is possible under the basic conditions leading to esters of type 392. 

Synthesis of 153 began with 4-hydroxy-lH-quinolin-2-one 156 which was heated in refluxing diphenyl ether (boiling point = 259 °C) with p-anisidinc... 

A solution of diethyl (2,3,4-trifluorophenylamino)(p-methoxybenzyl-thio)methylenemalonate in diphenyl ether was added to diphenyl ether at 110°C, and the reaction mixture was then stirred at 250-260°C for 20 min under nitrogen to give ethyl 4-hydroxy-2-(/>-methoxyphenylthio)-6,7,8-trifluoroquinoline-3-carboxylate in 82% yield (88EUP286089). 

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