Biphenol synthesis

NMP are examples of suitable solvents for PES and PPSF polymerizations. Chlorobenzene or toluene are used as cosolvents at low concentrations. These cosolvents form an azeotrope with water as they distill out of the reaction mixture, thereby keeping the polymerization medium dehydrated. Potassium carbonate is a suitable choice for base. The synthesis of PES and PPSE differ from the PSE case in that the reaction is carried out in a single-step process. In other words, the formation of the dipotassium salt of the bisphenol is not completed in a separate first step. Equations 2 and 3 represent polymerizations based on the dipotassium salts of bisphenol S and biphenol to make PES and PPSE, respectively. 

Robeson and Matzner were the first to report the synthesis of the sulfonation of DCDPS.205 This work makes it possible to synthesize sulfonated poly(arylene ether sulfone) with well-controlled structures. Ueda et al. used this monomer (Scheme 6.27) as a comonomer of DCDPS to react with bisphenol A and high-molecular-weight bisphenol-A-based copolymers with up to 30 mol % sulfonation achieved.206 Biphenol-based copolymers with up to 100 mol % sulfonation were recently reported by Wang et al.207... 

Biomedical applications, 27 Bionolle, 28, 42, 43 Biopol polyesters, 28, 41 Bioresorbable polyesters, 27 synthesis of, 99-101 Biphenol-based copolymers, 356 Bis(aryloxy) monomers, polymerization of, 347... 

Previous studies by Sorokin with iron phthalocyanine catalysts made use of oxone in the oxidation of 2,3,6-trimethylphenol [134]. Here, 4 equiv. KHSO5 were necessary to achieve full conversion. Otherwise, a hexamethyl-biphenol is observed as minor side-product. Covalently supported iron phthalocyanine complexes also showed activity in the oxidation of phenols bearing functional groups (alcohols, double bonds, benzylic, and allylic positions) [135]. Besides, silica-supported iron phthalocyanine catalysts were reported in the synthesis of menadione [136]. 

Mikami and co-workers16-19 have done extensive work for developing catalysts for the asymmetric carbonyl-ene reaction. Excellent enantioselectivites are accessible with the binol-titanium catalyst 17 (Equation (10)) for the condensation of 2-methyl butadiene (R1 = vinyl) and glyoxalates (binol = l,T-binaphthalene-2,2 -diol).16 The products were further manipulated toward the total synthesis of (i )-(-)-ipsdienol. The oxo-titanium species 18 also provides excellent enantioselectivity in the coupling of a-methyl styrene with methyl glyoxalate.17 Reasonable yields and good enantioselectivites are also obtained when the catalyst 19 is formed in situ from titanium isopropoxide and the binol and biphenol derivatives.18... 

Direct copolymerization techniques have also been employed in the s)m-thesis of sulfonated poly(aryl ether ketones),i i polyimides, i 5 and poly(benzoimidazoles). The synthesis of random disulfonated biphenol poly(arylene ether sulfone) copolymers (BPSH x where x represents the percentage of disulfonated diphenylsulfone moieties in the polymer versus unsulfonated diphenylsulfone moities) (14) is shown in Scheme 3.5. 

Scheme 4 Synthesis of ClMeO-biphenol-based phosphite 19a...

Schemes One-pot synthesis of ClMeO-biphenol-based phosphites 19b,c...

The Ullmann coupling is the classical example of Cu-catalyzed biaryl coupling, wherein (a) a phenol and arylhalide substrate are converted to a bis-arylether or (b) two arenes are coupled to form a bis-arene species. These coupling reactions are of great importance for general organic synthesis as well as pharmaceutical and fine chemicals. The copper-catalyzed phenol coupling to arrive at chiral biphenol derivatives is used extensively as a test reaction for the catalytic activity of new copper complexes [254,255]. 

Synthesis of high Tg co-polycarbonates containing 3,3-bis(4-hydroxyphenyl)-l-phenyl-lH- indol-2-one and bisphenol A biphenols, which adhere to aluminum. 

Some simple biphenols equipped with methyl groups, e.g., 3,3, 5,5 -tetramethyl-2,2 -biphenol 38, have attracted attention as important components of highly potent ligand systems [75-86]. Remarkably, the sustainable synthesis of such biphenols is rather challenging despite their simple scaffolds. In particular, methyl-substituted phenols are prone to side reactions. This is especially the case when 2,4-dimethyl-phenol (37) is oxidatively treated. Upon anodic conversion 37 is preferably transformed into polycyclic architectures [87]. Direct electrolysis in basic media provided only traces of the desired biphenol 38 and the dominating components of the product mixture consisted of Pu in meter s ketone 39 and the consecutive pentacyclic spiro derivative 40 [88]. For an efficient electrochemical access to 3,3, 5,5 -tetramethyl-2,2,-biphenol (38) we developed a boron-based template strategy [89, 90]. This methods requires a multi-step protocol but can be conducted on a multi-kilogram scale (Scheme 17). 

A related system permitted the synthesis of aromatic polycarbonates (PCs) via oxidative carbonylation [24] of a biphenol [25]. High yields ( 80%) with close to industrially useful molecular weight (Mn = 94 000) were obtained in this case (Scheme 5). 

Gribkov, D.V., Hultzsch, K.C., and Hampel, F. (2003) Synthesis and characterization of new biphenolate and binaphtholate rare-earth-metal amido complexes catalysts for asymmetric olefin hydroamination/cyclization. Chemistry - A European Journal, 9, 4796. 

Stable pentacoordinated allylsiliconates have been employed in aldehyde addition reactions. These reagents require no activation by Lewis acids or Lewis bases, but have found only limited applications in synthesis to date. The use of these agents in addition to aldehydes was first described in 1987 by Corriu [59] and Hosomi [60] and by Kira and Sakurai [61] in 1988. In these reactions, the addition of a catechol or 2,2 -biphenol-derived allylsiliconate to an achiral aldehyde led to the highly regio- and stereoselective formation of homoallylic alcohols. For example, the addition of the catechol-derived 2-butenylsiliconate 81 (90/10 E Z) provided a diastereomeric mixture of homoallylic alcohols 74 and 75 in a 90/10 ratio (Scheme 10-33) [60c]. 

B. Organic Synthesis Using Metal Complexes of Biphenol ... 

Metal phenoxides are utilized extensively in organic synthesis as reagents, since they can readily be prepared from phenols and appropriate metal reagents, and the phenol moiety can easily be modified either sterically or electronically. Particularly, 2,2 -dihydroxy-l,l -binaphthyl (BINOL), salicylideneamine and Af,Af -ethylenebis(salicylideneamine) (salen) proved to be excellent phenol ligands for asymmetric synthesis. Since some of their reactions have recently been reviewed , it may not be appropriate to reproduce all of them. Instead, this section concentrates on the effect of the phenol moiety on the chemical reactivity and selectivity, and tries to provide structure-activity relationships for the metal phenoxide reagents. Metalated derivatives of monophenols, biphenols and salicylaldehyde imines are discussed separately. 

N,N -Dimethyl-1,2-diphenylethylenediamine and related chiral diamines are not only useful chiral auxiliaries in asymmetric synthesis, but they have also found applications as analytical reagents. They allow the resolution and the determination of enantiomeric composition of aldehydes by formation of diastereomeric aminals.31 34 Combined with PCI3, they allow determination of the enantiomeric composition of alcohols, biphenols, thiols and amines.35 36 The diamine described here is used most extensively. 

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