Hydroxy-substituted -complexes

Platinum-group metals (qv) form complexes with chelating polymers with various 8-mercaptoquinoline [491-33-8] derivatives (83) (see Chelating agents). Hydroxy-substituted quinolines have been incorporated in phenol—formaldehyde resins (84). Stannic chloride catalyzes the condensation of bis(chloromethyl)benzene with quinoline (85). 

The application of this procedure to (racemic) hydroxy-substituted allylmolybdenum complexes, such as 3, yields diastereomerically pure 1,3-diols (e.g. ) or 1,3,5-triols (e.g. ) via the corresponding 1,3-dioxanes6 4 ... 

Hydroxy-substituted iron-acyl complexes 1, which are derived from aldol reactions of iron-acyl enolates with carbonyl compounds, are readily converted to the corresponding /i-methoxy or /1-acetoxy complexes 2 on deprotonation and reaction of the resulting alkoxide with iodomethane or acetic anhydride (Tabic 1). Further exposure of these materials to base promotes elimination of methoxide or acetate to provide the a,/ -unsaturated complexes (E)-3 and (Z)-3 (Table 2). 

The Dotz benzannulation reaction yields either arene chromium tricarbonyl complexes or the decomplexed phenols, depending on the work-up conditions. Because of the instability of hydroxy-substituted arene chromium tricarbonyl complexes, yields of the latter tend to be low. High yields of arene complexes can, however, be obtained by in situ silylation of the crude product of the benzannulation reaction [336]. Oxidative work-up yields either decomplexed phenols or the corresponding quinones. Treatment of the benzannulation products with phosphines also leads to decomplexed phenols [272]. 

In acceptor-substituted carbene complexes with hydrogen at Cp fast hydride migration to the carbene will usually occur [1094,1095]. The resulting olefins are often formed with high stereoselectivity. 1,2-Hydride migration will also occur in P-hydroxy carbene complexes, ketones being formed in high yields (Table 4.2). Intramolecular 1,5-C-H insertion can sometimes compete efficiently with 1,2-insertion [1096]. 

The reactions are those of functionalized 1-alkynes, the first of which were described for alkynes bearing substituted hydroxymethyl groups, such as substituted propargyl alcohols, HC=CCRR (OH), and often proceed further to form metal allenylidene complexes, by spontaneous dehydration of a (usually unobserved) hydroxy-vinylidene complex (Equation 1.22) ... 

The stoichiometric selective oxidation of the benzyhc alcohol function in (di)hydroxy-substituted benzylalcohols (Eq. 14) has been demonstrated by Nolte et al., using host-guest chemistry to steer the regiospecificity in the reaction [167-170]. The host-receptor used to construct dicopper complex 21 is based on the building block diphenylglycoluril, which was functionahzed... 

The copper-catalyzed photobicyclization of acyclic 1,6-dienes to bicyclo[3.2,0]heptanes using the bis[copper(l) lrifluoromethanesulfonate]benzene complex has found general and synthetic utility in the conversion of diallyl and homoallyl vinyl ethers to 3- or 2-oxabicyclo[3.2.0]heptanes,5 6 of /V-allyl-A -2-methyl-2-propenecarbamates to iV-carboethoxy-3-azabicyclo[3.2.0]heptanes 7 and of allylic alcohols to the corresponding hydroxy-substituted bicyclo[3.2.0]heptanes.8 9 Examples of such reactions are summarized below. 

The specific proposal is that the hydroxide attacks the 2- or the 4-position of the co-ordinated pyridine to form a hydroxy-substituted 1,2- or 1,4-dihydropyridine (Fig. 8-17). These hydroxy species are known as pseudo-bases. This behaviour is fully in accord with the known behaviour of A-alkylpyridinium cations. Although the pseudo-bases of simple A-alkylpyridinium cations are not dominant solution species under aqueous conditions, those derived from a variety of other nitrogen heterocycles are readily formed and are well-known. The suggestions had the advantage of linking the apparently divergent fields of heterocyclic and co-ordination chemistry by explaining some well-documented anomalies in the reactivity of pyridine complexes. 

As an example of conversion of complex 111 to 113, optically pure complex 126 was used for the enantioselective total synthesis of shikimic acid (129) [30]. The hydroxy-substituted diene complex 127 was prepared from 126. Silylation and decomplexation of 127 gave 128. Stereoselective dihydroxylation of the more reactive double bond of the decomplexed silyl ether derivative 128, followed by desilylation afforded (—)-methyl shikimate (129). 

Catalytic oxidation of 239 to the quinone 240 was also effected with H2O2 catalyzed by methyltrioxorhenium(VII) (McRcOb) (Scheme 60)", where a small amount of hydroxy-substituted quinone 280 was produced in addition to 240 (70%). In this reaction, MeRe03 is stepwise converted by H2O2 into the mono- and bis(peroxo)rhenium complex MeRe(02)20-H20 (281). This active oxidant then reacts with the phenol to give the epoxide 282, which is further converted to the two quinones (240 and 280). 

The cleavage activity of the monocyclic compounds listed in Scheme 19.8 against DNA is generally only moderate, with EC50 around 500 pM and with D/S ratios <1 15. In order to increase the potency, the hydroxy substituted derivatives 30 and 35 have been extensively used for the preparation of conjugated compounds where a DNA complexing subunit is attached to the OH group. 

The intramolecular Mannich reaction has been combined with the facile [3,3] sigmatropic rearrangement of iminium cations to provide a versatile synthesis of 3-acylpyrrolidines and other more complex ring systems containing this subunit.In the simplest case, a homoallylic amine with alkoxy or hydroxy substitution at the allylic site is allowed to react with an aldehyde in the presence of an equivalent or less of acid to yield substituted 3-acylpyrrolidine products (Scheme 50). The mild conditions of this transformation—which occurs at near ambient temperature and neutral pH—are apparent in the success of this sequence with labile aldehydes such as furfural. Ketones can be employed also in this case a two-step... 

The physiological activity of sulfides increases with molecular weight and complexity. Diethyl sulfide has been found to cause gastroenteritis. More complex compounds like allyl sulfides display antiseptic properties. Polyvinyl sulfides have a bactericidal effect. Nitro-, chloro-, and hydroxy-substituted diaryl sulfides possess insecticidal properties. 

Figure 6-5 lists most of the pyrrole-, thiophene-, amino- and hydroxy-substituted porphyrins employed for electropolymerization and the references. Monomers 49a - k [136-147] are based on synthetic porphyrins and 50a, b on deuteroporphyrin [148-150]. Surprisingly, the electrooxidation of metal complexes of protoporphyrin-DC dimethyl ester, possibly via the vinyl groups, leads to the deposition of electroactive porphyrin films on the electrode surface [151-153],... 

Sahin, Nieger, and Brdse have reported also the oxidative coupling of various hexahydro-xanthenols. The application of an iron complex as oxidant converted the 2-hydroxy-substituted xanthenes 1056 (Scheme 13.26) to the 3,3- t S-coupled biaryl 1057 (565). It appears that these two papers ((564) and (674)) represent the only chemical studies published on the topic of xanthone or xanthene biaiyl-coupUng. 

The use of the terminally hydroxy-substituted tetraene substrate 34 in this reaction made it possible to determine the stereochemistry of the overall 1,4-addition of the carbon and oxygen functions to the diene (Eq. (11.25)) [51]. Palladium-catalyzed reaction of 34 in THF under reflux afforded product 36 in which a net antt-1,4-addition had occurred. The stereochemistry was consistent with an intermediate 7i-allyl complex 35, in which carbon and palladium have added to the upper diene in a syn manner. Intramolecular attack by the hydroxy group from the face opposite to that of palladium would give the product observed. In this reaction, an interesting 1,2-stereoinduction by the methyl group occurred. 

Oxidative Eiectropoiymerization of Poiypyridyi Compiexes. Oxidative electropolymerization of suitably substituted [M (bipy)3l + complexes offers an alternative approach to the preparation of electrochromic redox active polymer films. Oxidative eiectropoiymerization has been described for iron(II) and ruthenium(II) complexes containing amino-substituted (31) and pendant aniline-substituted (32) 2,2 -bipyridyl ligands, and amino- and hydroxy-substituted 2,2 6, 2"-terpyridinyl ligands (33) [ligand structures (4) and (5)]. Analysis of IR spectra suggests that the eiectropoiymerization of [Ru(L )2l + [L = (4)], via the pendant aminophenyl substituent, proceeds by a reaction mechanism similar to that of aniline (33). The resulting metallopolymer film reversibly switches from purple to pale pink on oxidation of Fe(II) to Fe(III). For polymeric films formed from [Ru(L )2l + [L = (5)], via polymerization of the pendant hydroxyphenyl group, the color switch is from brown to dark yellow (see Electropolymerization). 

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